37. Secure Technologies

37.1. Hash Overview

For the purposes of this specification, a hash function takes a variable length input and generates a fixed length hash value. In general, hash functions are collision-resistant, which means that it is infeasible to find two distinct inputs which produce the same hash value. Hash functions are generally one-way which means that it is infeasible to find an input based on the output hash value.

This specification describes a protocol which allows a driver to produce a protocol which supports zero or more hash functions.

37.1.1. Hash References

The following references define the standard means of creating the hashes used in this specification:

Secure Hash Standard (SHS) (FIPS PUB 180-3), National Institute of Standards and Technology (October 2008).

For more information

see “Links to UEFI-Related Documents” at http://uefi.org/uefi under the heading “Archived FIPS publication”.
see “Links to UEFI-Related Documents” at http://uefi.org/uefi under the heading “MD5 Message-Digest Algorithm”. EFI Hash Protocols

37.1.1.1. EFI_HASH_SERVICE_BINDING_PROTOCOL

Summary

The EFI Hash Service Binding Protocol is used to locate hashing services support provided by a driver and create and destroy instances of the EFI Hash Protocol so that a multiple drivers can use the underlying hashing services.

The EFI Service Binding Protocol that is defined in EFI Services Binding defines the generic Service Binding Protocol functions. This section discusses the details that are specific to the EFI Hash Protocol.

GUID

#define EFI_HASH_SERVICE_BINDING_PROTOCOL_GUID \
  {0x42881c98,0xa4f3,0x44b0,\
    {0xa3,0x9d,0xdf,0xa1,0x86,0x67,0xd8,0xcd}}

Description

An application (or driver) that requires hashing services can use one of the protocol handler services, such as BS->LocateHandleBuffer(), to search for devices that publish an EFI Hash Service Binding Protocol.

After a successful call to the EFI_HASH_SERVICE_BINDING_PROTOCOL.CreateChild() function, the child EFI Hash Protocol driver instance is ready for use. The instance of EFI_HASH_PROTOCOL must be obtained by performing HandleProtocol() against the handle returned by CreateChild(). Use of other methods, such as LocateHandle(), are not supported.

Once obtained, the driver may use the EFI_HASH_PROTOCOL instance for any number of non-overlapping hash operations. Overlapping hash operations require an additional call to EFI_HASH_SERVICE_BINDING_PROTOCOL. CreateChild() for a new instance.

Before a driver or application terminates execution, every successful call to the EFI_HASH_SERVICE_BINDING_PROTOCOL.CreateChild() function must be matched with a call to the EFI_HASH_SERVICE_BINDING_PROTOCOL.DestroyChild() function.

37.1.1.2. EFI_HASH_PROTOCOL

Summary

This protocol describes standard hashing functions.

GUID

#define EFI_HASH_PROTOCOL_GUID \
  {0xc5184932,0xdba5,0x46db,\
    {0xa5,0xba,0xcc,0x0b,0xda,0x9c,0x14,0x35}}

Protocol Interface Structure

typedef _EFI_HASH_PROTOCOL {
  EFI_HASH_GET_HASH_SIZE      GetHashSize;
  EFI_HASH_HASH               Hash;
}   EFI_HASH_PROTOCOL;

Parameters

GetHashSize: Return the size of a specific type of resulting hash.
Hash: Create a hash for the specified message.

Description

This protocol allows creating a hash of an arbitrary message digest using one or more hash algorithms. The GetHashSize returns the expected size of the hash for a particular algorithm and whether or not that algorithm is, in fact, supported. The Hash actually creates a hash using the specified algorithm.

Related Definitions

None.

37.1.1.3. EFI_HASH_PROTOCOL.GetHashSize()

Summary

Returns the size of the hash which results from a specific algorithm.

Prototype

EFI_STATUS
EFIAPI
GetHashSize(
  IN CONST EFI_HASH_PROTOCOL     *This,
  IN CONST EFI_GUID              *HashAlgorithm,
  OUT UINTN                      *HashSize
);

Parameters

This: Points to this instance of EFI_HASH_PROTOCOL.
HashAlgorithm: Points to the EFI_GUID which identifies the algorithm to use. See EFI Hash Algorithms .
HashSize: Holds the returned size of the algorithm’s hash.

Description

This function returns the size of the hash which will be produced by the specified algorithm.

Related Definitions

None

Status Codes Returned

EFI_SUCCESS	Hash size returned successfully.
EFI_INVALID_PARAMETER	HashSize is NULL or HashAlgorithm is NULL.
EFI_UNSUPPORTED	The algorithm specified by HashAlgorithm is not supported by this driver.

37.1.1.4. EFI_HASH_PROTOCOL.Hash()

Summary

Creates a hash for the specified message text.

Prototype

EFI_STATUS
EFIAPI
Hash(
  IN CONST EFI_HASH_PROTOCOL     *This,
  IN CONST EFI_GUID              *HashAlgorithm,
  IN BOOLEAN                     Extend,
  IN CONST UINT8                 *Message,
  IN UINT64                      MessageSize,
  IN OUT EFI_HASH_OUTPUT         *Hash
);

Parameters

This: Points to this instance of EFI_HASH_PROTOCOL.
HashAlgorithm: Points to the EFI_GUID which identifies the algorithm to use. See EFI Hash Algorithms .
Extend: Specifies whether to create a new hash ( FALSE ) or extend the specified existing hash ( TRUE ).
Message: Points to the start of the message.
MessageSize: The size of Message, in bytes. Must be integer multiple of block size.
Hash: On input, if Extend is TRUE, then this parameter holds a pointer to a pointer to an array containing the hash to extend. If Extend is FALSE, then this parameter holds a pointer to a pointer to a caller-allocated array that will receive the result of the hash computation. On output (regardless of the value of Extend ), the array will contain the result of the hash computation.

Description

This function creates the hash of the specified message text based on the specified algorithm HashAlgorithm and copies the result to the caller-provided buffer Hash. If Extend is TRUE, then the hash specified on input by Hash is extended. If Extend is FALSE, then the starting hash value will be that specified by the algorithm.

NOTE: For the all algorithms used with EFI_HASH_PROTOCOL, the following apply:

The EFI_HASH_PROTOCOL.Hash() function does not perform padding of message data for these algorithms. Hence, MessageSize shall always be an integer multiple of the HashAlgorithm block size, and the final supplied Message in a sequence of invocations shall contain caller-provided padding. This will ensure that the final Hash output will be the correct hash of the provided message(s).
The result of a Hash() call for one of these algorithms when the caller does not supply message data whose length is an integer multiple of the algorithm’s block size is a returned error.
The EFI_HASH_OUTPUT options for these two algorithms shall be EFI_SHA1_HASH and EFI_SHA256_HASH, respectively.
Callers using these algorithms may consult the aforementioned Secure Hash Standard for details on how to perform proper padding required by standard prior to final invocation.

Related Definitions

EFI_HASH_OUTPUT

Status Codes Returned

EFI_SUCCESS	Hash returned successfully.
EFI_INVALID_PARAMETER	Message or Hash,HashAlgorithm i s NULL or MessageSize is 0. MessageSize is not an integer multiple of block size.
EFI_UNSUPPORTED	The algorithm specified by HashAlgorithm is not supported by this driver. Includes HashAlgorithm being passed as a null error.
EFI_UNSUPPORTED	Extend is TRUE and the algorithm doesn’t support extending the hash.

37.1.2. Other Code Definitions

37.1.2.1. EFI_SHA1_HASH, EFI_SHA224_HASH, EFI_SHA256_HASH,EFI_SHA384_HASH, EFI_SHA512HASH, EFI_MD5_HASH

Summary

Data structure which holds the result of the hash.

Prototype

typedef UINT8 EFI_MD5_HASH[16];
typedef UINT8 EFI_SHA1_HASH[20];
typedef UINT8 EFI_SHA224_HASH[28];
typedef UINT8 EFI_SHA256_HASH[32];
typedef UINT8 EFI_SHA384_HASH[48];
typedef UINT8 EFI_SHA512_HASH[64];
typedef union _EFI_HASH_OUTPUT {
  EFI_MD5_HASH       *Md5Hash;
  EFI_SHA1_HASH      *Sha1Hash;
  EFI_SHA224_HASH    *Sha224Hash;
  EFI_SHA256_HASH    *Sha256Hash;
  EFI_SHA384_HASH    *Sha384Hash;
  EFI_SHA512_HASH    *Sha512Hash;
}   EFI_HASH_OUTPUT;

Description

These prototypes describe the expected hash output values from the Hash function of the EFI_HASH_PROTOCOL.

Related Definitions

None

37.1.2.2. EFI Hash Algorithms

The following table gives the EFI_GUID for standard hash algorithms and the corresponding ASN.1 OID (Object Identifier):

Table 37.1 EFI Hash Algorithms
Algorithm	EFI_GUID	OID
SHA-1 (No padding done by implementation)	#define EFI_HASH_ALGO RITHM_SHA1_NOPAD_GUID {0x24c5dc2f, 0x53e2, 0x40ca, {0x9e, 0xd6, 0xa5, 0xd9, 0xa4, 0x9f, 0x46, 0x3b}}	id-sha1 OBJECT IDENTIFIER ::= { iso(1) ide ntified-organization( 3) oiw(14) secsig(3) algorithms(2) 26 }
SHA-256 (No padding done by implementation)	#define EFI_HASH_ALGORI THM_SHA256_NOPAD_GUID {0x8628752a, 0x6cb7, 0x4814, {0x96, 0xfc, 0x24, 0xa8, 0x15, 0xac, 0x22, 0x26}}	id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t (2) country (16) us (840) organization (1) gov (101) csor (3) nistalgorithm (4) hashalgs (2) 1}

Note: For the EFI_HASH_ALGORITHM_SHA1_NOPAD_GUID and the EFI_HASH_ALGORITHM_SHA256_NOPAD_GUID, the following apply:

The EFI_HASH_PROTOCOL.Hash() function does not perform padding of message data for these algorithms. Hence, MessageSize shall always be an integer multiple of the HashAlgorithm block size, and the final supplied Message in a sequence of invocations shall contain caller-provided padding. This will ensure that the final Hash output will be the correct hash of the provided message(s).
The result of a Hash() call for one of these algorithms when the caller does not supply message data whose length is an integer multiple of the algorithm’s block size is undefined.
The EFI_HASH_OUTPUT options for these two algorithms shall be EFI_SHA1_HASH and EFI_SHA256_HASH, respectively.
Callers using these algorithms may consult the aforementioned Secure Hash Standard for details on how to perform proper padding.

37.2. Hash2 Protocols

37.2.1. EFI Hash2 Service Binding Protocol

37.2.1.1. EFI_HASH2_SERVICE_BINDING_PROTOCOL

Summary

The EFI Hash2 Service Binding Protocol is used to locate EFI_HASH2_PROTOCOL hashing services support provided by a driver and create and destroy instances of the EFI_HASH2_PROTOCOL Protocol so that a multiple drivers can use the underlying hashing services.

The EFI Service Binding Protocol that is defined in EFI Services Binding defines the generic Service Binding Protocol functions. This section discusses the details that are specific to the EFI Hash Protocol.

GUID

#define EFI_HASH2_SERVICE_BINDING_PROTOCOL_GUID \
{0xda836f8d, 0x217f, 0x4ca0, 0x99, 0xc2, 0x1c, \
0xa4, 0xe1, 0x60, 0x77, 0xea}

Description

An application (or driver) that requires hashing services can use one of the protocol handler services, such as BS->LocateHandleBuffer(), to search for devices that publish an EFI_HASH2_SERVICE_BINDING_PROTOCOL.

After a successful call to the EFI_HASH2_SERVICE_BINDING_PROTOCOL member CreateChild() function, the child instance of EFI_HASH2_PROTOCOL Protocol driver instance is ready for use. The instance of EFI_HASH2_PROTOCOL must be obtained by performing HandleProtocol() against the handle returned by CreateChild(). Use of other methods, such as LocateHandle() is not supported.

Once obtained, the driver may use the EFI_HASH2_PROTOCOL instance for any number of non-overlapping hash operations. Overlapping hash operations require an additional call to EFI_HASH_SERVICE_BINDING_PROTOCOL. CreateChild() for a new instance.

Before a driver or application using the instance terminates execution, every successful call to the EFI_HASH_SERVICE_BINDING_PROTOCOL.CreateChild() function must be matched with a call to the EFI_HASH_SERVICE_BINDING_PROTOCOL.DestroyChild() function.

37.2.2. EFI Hash2 Protocol

37.2.2.1. EFI_HASH2_PROTOCOL

Summary

This protocol describes hashing functions for which the algorithm-required message padding and finalization are performed by the supporting driver.

GUID

#define EFI_HASH2_PROTOCOL_GUID \
{
0x55b1d734, 0xc5e1, 0x49db, 0x96, 0x47, 0xb1, 0x6a, \
0xfb, 0xe, 0x30, 0x5b}

Protocol Interface Structure

typedef _EFI_HASH2_PROTOCOL {
  EFI_HASH2_GET_HASH_SIZE        GetHashSize;
  EFI_HASH2_HASH                 Hash;
  EFI_HASH2_HASH_INIT            HashInit;
  EFI_HASH2_HASH_UPDATE          HashUpdate;
  EFI_HASH2_HASH_FINAL           HashFinal;
}   EFI_HASH2_PROTOCOL;

Parameters

GetHashSize: Return the result size of a specific type of resulting hash.
Hash: Create a final non-extendable hash for a single message block in a single call.
HashInit: Initializes an extendable multi-part hash calculation
HashUpdate: Continues a hash in progress by supplying the first or next sequential portion of the message text
HashFinal: Finalizes a hash in progress by padding as required by algorithm and returning the hash output.

Description

This protocol allows creating a hash of an arbitrary message digest using one or more hash algorithms. The GetHashSize() function returns the expected size of the hash for a supported algorithm and an error if that algorithm is not supported. The Hash() function creates a final, non-extendable, hash of a single message block using the specified algorithm. The three functions HashInit(), HashUpdate(), HashFinal(), generates the hash of a multi-part message, with input composed of one or more message pieces.

For a specific handle representing an instance of EFI_HASH2_PROTOCOL, if Hash() is called after a call to HashInit() and prior to the matching call to HashFinal() , the multi-part hash started by HashInit() will be canceled and calls to HashUpdate() or HashFinal() will return an error status unless proceeded by a new call to HashInit().

NOTE: Algorithms EFI_HASH_ALGORITHM_SHA1_NOPAD and EFI_HASH_ALGORITHM_SHA256_NOPAD_GUID are not compatible with EFI_HASH2_PROTOCOL and will return EFI_UNSUPPORTED if used with any EFI_HASH2_PROTOCOL function.

Related Definitions

None

NOTE: The following hash function invocations will produce identical hash results for all supported EFI_HASH2_PROTOCOL algorithms. The data in quotes is the message.

Table 37.2 Identical Hash Results
Hash(“ABCDEF”)	HashInit()	HashInit ()
	HashUpdate(“ABCDEF”)	HashUpdate (“ABC”)
	HashFinal()	HashUpdate (“DE”)
		HashUpdate (“F”)
		HashFinal ()

_images/Secure_Technologies-2.png — Fig. 37.1 **Hash workflow**

37.2.2.2. EFI_HASH2_PROTOCOL.GetHashSize()

Summary

Returns the size of the hash which results from a specific algorithm.

Prototype

EFI_STATUS
EFIAPI
GetHashSize(
  IN  CONST EFI_HASH2_PROTOCOL             *This,
  IN  CONST EFI_GUID                       *HashAlgorithm,
  OUT  UINTN                               *HashSize
  );

Parameters

This: Points to this instance of EFI_HASH2_PROTOCOL.
HashAlgorithm: Points to the EFI_GUID which identifies the algorithm to use. See Other Code Definitions .

HashSize: Holds the returned size of the algorithm’s hash.

Description

This function returns the size of the hash result buffer which will be produced by the specified algorithm.

Related Definitions

None

Status Codes Returned

EFI_SUCCESS	Hash size returned successfully.
EFI_INVALID_PARAMETER	This or HashSize is NULL
EFI_UNSUPPORTED	The algorithm specified by HashAlgorithm is not supported by this driver or, HashAlgorithm is NULL.

37.2.2.3. EFI_HASH2_PROTOCOL.Hash()

Summary

Creates a hash for a single message text. The hash is not extendable. The output is final with any algorithm-required padding added by the function.

Prototype

EFI_STATUS
EFIAPI
Hash(
  IN CONST EFI_HASH2_PROTOCOL       *This,
  IN CONST EFI_GUID                 *HashAlgorithm,
  IN CONST UINT8                    *Message,
  IN UINTN                          MessageSize,
  IN OUT EFI_HASH2_OUTPUT           *Hash
);

Parameters

This: Points to this instance of EFI_HASH2_PROTOCOL.
HashAlgorithm: Points to the EFI_GUID which identifies the algorithm to use. See Table, Algorithms that may be used with EFI_HASH2_PROTOCOL.
Message: Points to the start of the message.
MessageSize: The size of Message, in bytes.
Hash: On input, points to a caller-allocated buffer of the size returned by GetHashSize() for the specified HashAlgorithm. On output, the buffer holds the resulting hash computed from the message.

Description

This function creates the hash of specified single block message text based on the specified algorithm HashAlgorithm and copies the result to the caller-provided buffer Hash. The resulting hash cannot be extended. All padding required by HashAlgorithm is added by the implementation.

Related Definitions

EFI_HASH2_OUTPUT

Status Codes Returned

EFI_SUCCESS	Hash returned successfully.
EFI_INVALID_PARAMETER	This, or Hash is NULL.
EFI_UNSUPPORTED	The algorithm specified by HashAlgorithm is not supported by this driver or HashAlgorithm is Null.
EFI_OUT_OF_RESOURCES	Some resource required by the function is not available or MessageSize is greater than platform maximum.

37.2.2.4. EFI_HASH2_PROTOCOL.HashInit()

Summary

This function must be called to initialize a digest calculation to be subsequently performed using the EFI_HASH2_PROTOCOL functions HashUpdate() and HashFinal().

Prototype

EFI_STATUS
EFIAPI
HashInit(
  IN CONST EFI_HASH2_PROTOCOL       *This,
  IN CONST EFI_GUID                 *HashAlgorithm,
);

Parameters

This: Points to instance of EFI_HASH2_PROTOCOL.
HashAlgorithm: Points to the EFI_GUID which identifies the algorithm to use. See Table, Algorithms that may be used with EFI_HASH2_PROTOCOL

Description

This function

Related Definitions

Status Codes Returned

EFI_SUCCESS	Initialized successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_UNSUPPORTED	The algorithm specified by HashAlgorithm is not supported by this function or HashAlgorithm is Null.
EFI_OUT_OF_RESOURCES	Process failed due to lack of required resource.
EFI_ALREADY_STARTED	This function is called when the operation in progress is still in processing Hash(), or HashInit() is already called before and not terminated by HashFinal() yet on the same instance.

37.2.2.5. EFI_HASH2_PROTOCOL.HashUpdate()

Summary

Updates the hash of a computation in progress by adding a message text.

Prototype

EFI_STATUS
EFIAPI
HashUpdate(
  IN CONST EFI_HASH2_PROTOCOL    *This,
  IN CONST UINT8                 *Message,
  IN UINTN                       MessageSize
);

Parameters

This: Points to instance of EFI_HASH2_PROTOCOL.
Message: Points to the start of the message.
MessageSize: The size of Message, in bytes.

Description

This function extends the hash of ongoing hash operation with the supplied message text. This function should be called one or more times with portions of the total message text to be hashed.. A zero-length message input will return EFI_SUCCESS and has no impacts on the ongoing hash instance.

Related Definitions

Status Codes Returned

EFI_SUCCESS	Digest in progress updated successfully.
EFI_INVALID_PARAMETER	This or Hash is NULL.
EFI_OUT_OF_RESOURCES	Some resource required by the function is not available or MessageSize is greater than platform maximum.
EFI_NOT_READY	This call was not preceded by a valid call to HashInit(), or the operation in progress was terminated by a call to Hash() or HashFinal() on the same instance.

37.2.2.6. EFI_HASH2_PROTOCOL.HashFinal()

Summary

Finalizes a hash operation in progress and returns calculation result. The output is final with any necessary padding added by the function. The hash may not be further updated or extended after HashFinal().

Prototype

EFI_STATUS
EFIAPI
HashFinal(
  IN CONST EFI_HASH2_PROTOCOL      *This,
  IN OUT EFI_HASH2_OUTPUT          *Hash
);

Parameters

This: Points to instance of EFI_HASH2_PROTOCOL.
Hash: On input, points to a caller-allocated buffer of the size returned by GetHashSize() for the specified HashAlgorithm specified in preceding HashInit(). On output, the buffer holds the resulting hash computed from the message.

Description

This function finalizes the hash of a hash operation in progress. The resulting final hash cannot be extended.

Related Definitions

EFI_HASH2_OUTPUT

Status Codes Returned

EFI_SUCCESS	Hash returned successfully.
EFI_INVALID_PARAMETER	This or Hash is NULL
EFI_NOT_READY	This call was not preceded by a valid call to HashInit() and at least one call to HashUpdate(), or the operation in progress was canceled by a call to Hash() on the same instance.

Table 37.3 Algorithms that may be used with *EFI_HASH2_PROTOCOL*
	EFI_GUID	OID
SHA-1	#define EFI_HASH _ALGORITHM_SHA1_GUID {0x2ae9d80f, 0x3fb2, 0x4095, { 0xb7, 0xb1, 0xe9, 0x31, 0x57, 0xb9, 0x46, 0xb6}}	id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified- organization(3) oiw(14) secsig(3) algorithms(2) 26 }
SHA-224	#define EFI_HASH _ALGORITHM_SHA224_GUI D { 0x8df01a06, 0x9bd5, 0x4bf7, { 0xb0, 0x21, 0xdb, 0x4f, 0xd9, 0xcc, 0xf4, 0x5b } }
SHA-256	#define EFI_HASH _ALGORITHM_SHA256_GUI D { 0x51aa59de, 0xfdf2, 0x4ea3, { 0xbc, 0x63, 0x87, 0x5f, 0xb7, 0x84, 0x2e, 0xe9 } }	id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t (2) country (16) us (840) organization (1) gov (101) csor (3) nistalgorithm (4) hashalgs (2) 1}
SHA-384	#define EFI_HASH _ALGORITHM_SHA384_GUI D { 0xefa96432, 0xde33, 0x4dd2, { 0xae, 0xe6, 0x32, 0x8c, 0x33, 0xdf, 0x77, 0x7a } }	id-sha384 OBJECT IDENTIFIER ::= { joint-iso-itu-t (2) country (16) us (840) organization (1) gov (101) csor (3) nistalgorithm (4) hashalgs (2) 2}
SHA-512	#define EFI_HASH _ALGORITHM_SHA512_GUI D { 0xcaa4381e, 0x750c, 0x4770, { 0xb8, 0x70, 0x7a, 0x23, 0xb4, 0xe4, 0x21, 0x30 } }	id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t (2) country (16) us (840) organization (1) gov (101) csor (3) nistalgorithm (4) hashalgs (2) 3}
MD5	#define EFI_HA SH_ALGORTIHM_MD5_GUID { 0xaf7c79c, 0x65b5, 0x4319, { 0xb0, 0xae, 0x44, 0xec, 0x48, 0x4e, 0x4a, 0xd7 } }	id-md5 OBJECT IDENTIFIER ::= { iso (1) member-body (2) us (840) rsadsi (113549) digestAlgorithm (2) 5}

NOTE: SHA-1 and MD5 are included for backwards compatibility. New driver implementations are encouraged to consider stronger algorithms.

37.2.3. Other Code Definitions

37.2.3.1. EFI_HASH2_OUTPUT

Summary

Data structure which holds the result of the hash operation from EFI_HASH2_PROTOCOL hash operations.

Prototype

typedef UINT8 EFI_MD5_HASH2[16];
typedef UINT8 EFI_SHA1_HASH2[20];
typedef UINT8 EFI_SHA224_HASH2[28];
typedef UINT8 EFI_SHA256_HASH2[32];
typedef UINT8 EFI_SHA384_HASH2[48];
typedef UINT8 EFI_SHA512_HASH2[64];
typedef union _EFI_HASH2_OUTPUT {
  EFI_MD5_HASH2         Md5Hash;
  EFI_SHA1_HASH2        Sha1Hash;
  EFI_SHA224_HASH2      Sha224Hash;
  EFI_SHA256_HASH2      Sha256Hash;
  EFI_SHA384_HASH2      Sha384Hash;
  EFI_SHA512_HASH2      Sha512Hash;
  } EFI_HASH2_OUTPUT;

Description

These prototypes describe the expected hash output values from the hashing functions of the EFI_HASH2_PROTOCOL.

Related Definitions

None

37.3. Key Management Service

37.3.1. EFI_KEY_MANAGEMENT_SERVICE_PROTOCOL

Summary

The Key Management Service (KMS) protocol provides services to generate, store, retrieve, and manage cryptographic keys. The intention is to specify a simple generic protocol that could be used for many implementations.

The management keys have a simple construct - they consist of key identifier and key data, both of variable size.

A driver implementing the protocol may need to provide basic key service that consists of a key store and cryptographic key generation capability. It may connect to an external key server over the network, or to a Hardware Security Module (HSM) attached to the system it runs on, or anything else that is capable of providing the key management service.

Authentication and access control is not addressed by this protocol. It is assumed it is addressed at the system level and done by the driver implementing the protocol, if applicable to the implementation.

GUID

#define EFI_KMS_PROTOCOL_GUID \
  {0xEC3A978D,0x7C4E, 0x48FA,\
  {0x9A,0xBE,0x6A,0xD9,0x1C,0xC8,0xF8,0x11}}

Protocol Interface Structure

#define EFI_KMS_DATA_TYPE_NONE      0
#define EFI_KMS_DATA_TYPE_BINARY    1
#define EFI_KMS_DATA_TYPE_ASCII     2
#define EFI_KMS_DATA_TYPE_UNICODE   4
#define EFI_KMS_DATA_TYPE_UTF8      8

Where appropriate, EFI_KMS_DATA_TYPE values may be combined using a bitwise ‘ OR ’ operation to indicate support for multiple data types.

typedef struct _EFI_KMS_SERVICE_PROTOCOL {
  EFI_KMS_GET_SERVICE_STATUS        GetServiceStatus;
  EFI_KMS_REGISTER_CLIENT           RegisterClient;
  EFI_KMS_CREATE_KEY                CreateKey;
  EFI_KMS_GET_KEY                   GetKey;
  EFI_KMS_ADD_KEY                   AddKey;
  EFI_KMS_DELETE_KEY                DeleteKey;
  EFI_KMS_GET_KEY_ATTRIBUTES        GetKeyAttributes;
  EFI_KMS_ADD_KEY_ATTRIBUTES        AddKeyAttributes;
  EFI_KMS_DELETE_KEY_ATTRIBUTES     DeleteKeyAttributes;
  EFI_KMS_GET_KEY_BY_ATTRIBUTES     GetKeyByAttributes;
  UINT32                            ProtocolVersion;
  EFI_GUID                          ServiceId;
  CHAR16                            *ServiceName;
  UINT32                            ServiceVersion;
  BOOLEAN                           ServiceAvailable;
  BOOLEAN                           ClientIdSupported;
  BOOLEAN                           ClientIdRequired;
  UINT16                            ClientIdMaxSize;
  UINT8                             ClientNameStringTypes;
  BOOLEAN                           ClientNameRequired;
  UINT16                            ClientNameMaxCount;
  BOOLEAN                           ClientDataSupported;
  UINTN                             ClientDataMaxSize;
  BOOLEAN                           KeyIdVariableLenSupported;
  UINTN                             KeyIdMaxSize;
  UINTN                             KeyFormatsCount;
  EFI_GUID                          *KeyFormats;
  BOOLEAN                           KeyAttributesSupported;
  UINT8                             KeyAttributeIdStringTypes;
  UINT16                            KeyAttributeIdMaxCount;
  UINTN                             KeyAttributesCount;
  EFI_KMS_KEY_ATTRIBUTE             *KeyAttributes;
}   EFI_KMS_PROTOCOL;

Parameters

GetServiceStatus

Get the current status of the key management service. If the implementation has not yet connected to the KMS, then a call to this function will initiate a connection. This is the only function that is valid for use prior to the service being marked available.

RegisterClient

Register a specific client with the KMS.

CreateKey

Request the generation of a new key and retrieve it.

GetKey

Retrieve an existing key.

AddKey

Add a local key to the KMS database. If there is an existing key with this key identifier in the KMS database, it will be replaced with the new key.

DeleteKey

Delete an existing key from the KMS database.

AddKeyAttributes

Add attributes to an existing key in the KMS database.

GetKeyAttributes

Get attributes for an existing key in the KMS database.

DeleteKeyAttributes

Delete attributes for an existing key in the KMS database.

GetKeyByAttributes

Get existing key(s) with the specified attributes.

ProtocolVersion

The version of this EFI_KMS_PROTOCOL structure. This must be set to 0x00020040 for the initial version of this protocol.

ServiceId

Optional GUID used to identify a specific KMS. This GUID may be supplied by the provider, by the implementation, or may be null. If it is null, then the*ServiceName* must not be null.

ServiceName

Optional pointer to a unicode string which may be used to identify the KMS or provide other information about the supplier.

ServiceVersion

Optional 32-bit value which may be used to indicate the version of the KMS provided by the supplier.

ServiceAvailable

TRUE if and only if the service is active and available for use. To avoid unnecessary delays in POST, this protocol may be installed without connecting to the service. In this case, the first call to the GetServiceStatus() function will cause the implementation to connect to the supported service and mark it as available. The capabilities of this service as defined in the remainder of this protocol are not guaranteed to be valid until the service has been marked available.

FALSE otherwise.

ClientIdSupported

TRUE if and only if the service supports client identifiers. Client identifiers may be used for auditing, access control or any other purpose specific to the implementation.

FALSE otherwise.

ClientIdRequired

TRUE if and only if the service requires a client identifier in order to process key requests.

FALSE otherwise.

ClientIdMaxSize

The maximum size in bytes for the client identifier.

ClientNameStringTypes

The client name string type(s) supported by the KMS service. If client names are not supported, this field will be set to EFI_KMS_DATA_TYPE_NONE. Otherwise, it will be set to the inclusive ‘OR’ of all client name formats supported. Client names may be used for auditing, access control or any other purpose specific to the implementation.

ClientNameRequired

TRUE if and only if the KMS service requires a client name to be supplied to the service.

FALSE otherwise.

ClientNameMaxCount

The maximum number of characters allowed for the client name.

ClientDataSupported

TRUE if and only if the service supports arbitrary client data requests. The use of client data requires the caller to have specific knowledge of the individual KMS service and should be used only if absolutely necessary.

FALSE otherwise.

ClientDataMaxSize

The maximum size in bytes for the client data. If the maximum data size is not specified by the KMS or it is not known, then this field must be filled with all ones.

KeyIdVariableLenSupported

TRUE if variable length key identifiers are supported.

FALSE if a fixed length key identifier is supported.

KeyIdMaxLen

If KeyIdVariableLenSupported is TRUE, this is the maximum supported key identifier length in bytes. Otherwise this is the fixed length of key identifier supported. Key ids shorter than the fixed length will be padded on the right with blanks.

KeyFormatsCount

The number of key format/size GUIDs returned in the KeyFormats field.

KeyFormats

A pointer to an array of EFI_GUID values which specify key formats/sizes supported by this KMS. Each format/size pair will be specified by a separate EFI_GUID . At least one key format/size must be supported. All formats/sizes with the same hashing algorithm must be contiguous in the array, and for each hashing algorithm, the key sizes must be in ascending order. See “Related Definitions” for GUIDs which identify supported key formats/sizes.

‘This list of GUIDs supported by the KMS is not required to be exhaustive, and the KMS may provide support for additional key formats/sizes. Users may request key information using an arbitrary GUID, but any GUID not recognized by the implementation or not supported by the KMS will return an error code of EFI_UNSUPPORTED.

KeyAttributesSupported

TRUE if key attributes are supported.

FALSE if key attributes are not supported.

KeyAttributeIdStringTypes

The key attribute identifier string type(s) supported by the KMS service. If key attributes are not supported, this field will be set to EFI_KMS_DATA_TYPE_NONE. Otherwise, it will be set to the inclusive ‘OR’ of all key attribute identifier string types supported. EFI_KMS_DATA_TYPE_BINARY is not valid for this field.

KeyAttributeIdMaxCount

The maximum number of characters allowed for the client name.

KeyAttributesCount

The number of predefined KeyAttributes structures returned in the KeyAttributes parameter. If the KMS does not support predefined key attributes, or if it does not provide a method to obtain predefined key attributes data, then this field must be zero.

KeyAttributes

A pointer to an array of KeyAttributes structures which contains the predefined attributes supported by this KMS. Each structure must contain a valid key attribute identifier and should provide any other information as appropriate for the attribute, including a default value if one exists. This variable must be set to NULL if the KeyAttributesCount variable is zero. It must point to a valid buffer if the KeyAttributesCount variable is non-zero.

This list of predefined attributes is not required to be exhaustive, and the KMS may provide additional predefined attributes not enumerated in this list. The implementation does not distinguish between predefined and used defined attributes, and therefore, predefined attributes not enumerated will still be processed to the KMS.

Related Definitions

Functions defined for this protocol typically require the caller to provide information about the client, the keys to be processed, and/or attributes of the keys to be processed. Four structures, EFI_KMS_CLIENT_INFO, EFI_KMS_KEY_DESCRIPTOR, EFI_KMS_DYNAMIC_ATTRIBUTE, and EFI_KMS_KEY_ATTRIBUTE define the information to be passed to these functions.

typedef struct {
  UINT16          ClientIdSize;
  VOID            *ClientId;
  UINT8           ClientNameType;
  UINT8           ClientNameCount;
  VOID            *ClientName;
}   EFI_KMS_CLIENT_INFO;

ClientIdSize: The size in bytes for the client identifier.
ClientId: Pointer to a valid client identifier.
ClientNameType: The client name string type used by this client. The string type set here must be one of the string types reported in the ClientNameStringTypes field of the KMS protocol. If the KMS does not support client names, this field should be set to EFI_KMS_DATA_TYPE_NONE.
ClientNameCount: The size in characters for the client name. This field will be ignored if ClientNameStringType is set to EFI_KMS_DATA_TYPE_NONE. Otherwise, it must contain number of characters contained in the ClientName field.
ClientName: Pointer to a client name. This field will be ignored if ClientNameStringType is set to EFI_KMS_DATA_TYPE_NONE. Otherwise, it must point to a valid string of the specified type.

The key formats recognized by the KMS protocol are defined by an EFI_GUID which specifies a (key-algorithm, key-size) pair. The names of these GUIDs are in the format EFI_KMS_KEY_(key-algorithm)_(key-size)_GUID, where the key-size is expressed in bits. The key formats recognized fall into three categories, generic (no algorithm), hash algorithms, and encrypted algorithms.

Generic Key Data:

The following GUIDs define formats that contain generic key data of a specific size in bits, but which is not associated with any specific key algorithm(s).

#define EFI_KMS_FORMAT_GENERIC_128_GUID \
  {0xec8a3d69,0x6ddf,0x4108,\
    {0x94,0x76,0x73,0x37,0xfc,0x52,0x21,0x36}}

#define EFI_KMS_FORMAT_GENERIC_160_GUID \
  {0xa3b3e6f8,0xefca,0x4bc1,\
    {0x88,0xfb,0xcb,0x87,0x33,0x9b,0x25,0x79}}

#define EFI_KMS_FORMAT_GENERIC_256_GUID \
  {0x70f64793,0xc323,0x4261,\
    {0xac,0x2c,0xd8,0x76,0xf2,0x7c,0x53,0x45}}

#define EFI_KMS_FORMAT_GENERIC_512_GUID \
  {0x978fe043,0xd7af,0x422e,\
    {0x8a,0x92,0x2b,0x48,0xe4,0x63,0xbd,0xe6}}

#define EFI_KMS_FORMAT_GENERIC_1024_GUID \
  {0x43be0b44,0x874b,0x4ead,\
    {0xb0,0x9c,0x24,0x1a,0x4f,0xbd,0x7e,0xb3}}

#define EFI_KMS_FORMAT_GENERIC_2048_GUID \
  {0x40093f23,0x630c,0x4626,\
    {0x9c,0x48,0x40,0x37,0x3b,0x19,0xcb,0xbe}}

#define EFI_KMS_FORMAT_GENERIC_3072_GUID \
  {0xb9237513,0x6c44,0x4411,\
    {0xa9,0x90,0x21,0xe5,0x56,0xe0,0x5a,0xde}}

#define EFI_KMS_FORMAT_GENERIC_DYNAMIC_GUID \
  {0x2156e996, 0x66de, 0x4b27, \
    {0x9c, 0xc9, 0xb0, 0x9f, 0xac, 0x4d, 0x2, 0xbe}}

The EFI_KMS_FORMAT_GENERIC_DYNAMIC_GUID is defined for the key data with a size not defined by a certain key format GUID. The key value specified by this GUID is in format of structure EFI_KMS_FORMAT_GENERIC_DYNAMIC.

typedef struct {
  UINT32          KeySize;
  UINT8           KeyData[1];
} EFI_KMS_FORMAT_GENERIC_DYNAMIC;

KeySize: Length in bytes of the KeyData.
KeyData: The data of the key.

Hash Algorithm Key Data:

These GUIDS define key data formats that contain data generated by basic hash algorithms with no cryptographic properties.

#define EFI_KMS_FORMAT_MD2_128_GUID \
  {0x78be11c4,0xee44,0x4a22,\
    {0x9f,0x05,0x03,0x85,0x2e,0xc5,0xc9,0x78}}

#define EFI_KMS_FORMAT_MDC2_128_GUID \
 {0xf7ad60f8,0xefa8,0x44a3,\
   {0x91,0x13,0x23,0x1f,0x39,0x9e,0xb4,0xc7}}

#define EFI_KMS_FORMAT_MD4_128_GUID \
 {0xd1c17aa1,0xcac5,0x400f,0xbe,\
   {0x17,0xe2,0xa2,0xae,0x06,0x67,0x7c}}

#define EFI_KMS_FORMAT_MDC4_128_GUID \
 {0x3fa4f847,0xd8eb,0x4df4,\
   {0xbd,0x49,0x10,0x3a,0x0a,0x84,0x7b,0xbc}}

#define EFI_KMS_FORMAT_MD5_128_GUID \
 {0xdcbc3662,0x9cda,0x4b52,\
   {0xa0,0x4c,0x82,0xeb,0x1d,0x23,0x48,0xc7}}

#define EFI_KMS_FORMAT_MD5SHA_128_GUID \
 {0x1c178237,0x6897,0x459e,\
   {0x9d,0x36,0x67,0xce,0x8e,0xf9,0x4f,0x76}}

#define EFI_KMS_FORMAT_SHA1_160_GUID \
 {0x453c5e5a,0x482d,0x43f0,\
   {0x87,0xc9,0x59,0x41,0xf3,0xa3,0x8a,0xc2}}

#define EFI_KMS_FORMAT_SHA256_256_GUID \
 {0x6bb4f5cd,0x8022,0x448d,\
   {0xbc,0x6d,0x77,0x1b,0xae,0x93,0x5f,0xc6}}

#define EFI_KMS_FORMAT_SHA512 512_GUID \
 {0x2f240e12,0xe14d,0x475c,\
   {0x83,0xb0,0xef,0xff,0x22,0xd7,0x7b,0xe7}}

Encryption Algorithm Key Data:

These GUIDs define key data formats that contain data generated by cryptographic key algorithms. There may or may not be a separate data hashing algorithm associated with the key algorithm.

#define EFI_KMS_FORMAT_AESXTS_128_GUID \
 {0x4776e33f,0xdb47,0x479a,\
   {0xa2,0x5f,0xa1,0xcd,0x0a,0xfa,0xb3,0x8b}}

#define EFI_KMS_FORMAT_AESXTS_256_GUID \
 {0xdc7e8613,0xc4bb,0x4db0,\
   {0x84,0x62,0x13,0x51,0x13,0x57,0xab,0xe2}}

#define EFI_KMS_FORMAT_AESCBC_128_GUID \
 {0xa0e8ee6a,0x0e92,0x44d4,\
   {0x86,0x1b,0x0e,0xaa,0x4a,0xca,0x44,0xa2}}

#define EFI_KMS_FORMAT_AESCBC_256_GUID \
 {0xd7e69789,0x1f68,0x45e8,\
   {0x96,0xef,0x3b,0x64,0x07,0xa5,0xb2,0xdc}}

#define EFI_KMS_FORMAT_RSASHA1_1024_GUID \
 {0x56417bed,0x6bbe,0x4882,\
   {0x86,0xa0,0x3a,0xe8,0xbb,0x17,0xf8,0xf9}}

#define EFI_KMS_FORMAT_RSASHA1_2048_GUID \
 {0xf66447d4,0x75a6,0x463e,\
   {0xa8,0x19,0x07,0x7f,0x2d,0xda,0x05,0xe9}}

#define EFI_KMS_FORMAT_RSASHA256_2048_GUID \
 {0xa477af13,0x877d,0x4060,
   {0xba,0xa1,0x25,0xd1,0xbe,0xa0,0x8a,0xd3}}

#define EFI_KMS_FORMAT_RSASHA256_3072_GUID \
 {0x4e1356c2,0xeed,0x463f,\
   {0x81,0x47,0x99,0x33,0xab 0xdb,0xc7,0xd5}}

The encryption algorithms defined above have the following properties

Table 37.4 Encryption Algorithm Properties
EFI_KMS_FORMAT	Encryption Description	Key Data Size	Hash Function
AESXTS_128	Symmetric encryption using XTS-AES 128 bit keys	Key data is a concatenation of two fields of equal size for a total size of 256 bits	N/A
AESXTS_256	Symmetric encryption using block cipher XTS-AES 256 bit keys	Key data is a concatenation of two fields of equal size for a total size of 512 bits	N/A
AESCBC_128	Symmetric encryption using block cipher AES-CBC 128 bit keys	128 bits	N/A
AESCBC_256	Symmetric encryption using block cipher AES-CBC 256 bit keys	256 bits	N/A
RSASHA1_1024	Asymmetric encryption using block cipher RSA 1024 bit keys	1024 bits	SHA1
RSASHA1_2048	Asymmetric encryption using block cipher RSA 2048 bit keys	2048 bits	SHA1
RSASHA256_2048	Asymmetric encryption using block cipher RSA 2048 bit keys	2048 bits	SHA256
RSASHA256_3072	Asymmetric encryption using block cipher RSA 3072 bit keys	3072 bits	SHA256

typedef struct {
  UINT8           KeyIdentifierSize;
  VOID            *KeyIdentifier;
  EFI_GUID        KeyFormat;
  VOID            *KeyValue;
  EFI_STATUS      KeyStatus;
}   EFI_KMS_KEY_DESCRIPTOR;

KeyIdentifierSize: The size of the KeyIdentifier field in bytes. This field is limited to the range 0 to 255.
KeyIdentifier: Pointer to an array of KeyIdentifierType elements.
KeyFormat: An EFI_GUID which specifies the algorithm and key value size for this key.
KeyValue: Pointer to a key value for a key specified by the KeyFormat field. A NULL value for this field indicates that no key is available.
KeyStatus: Specifies the results of KMS operations performed with this descriptor. This field is used to indicate the status of individual operations when a KMS function is called with multiple EFI_KMS_KEY_DESCRIPTOR structures. KeyStatus codes returned for the individual key requests are:

Status Codes Returned

EFI_SUCCESS	Successfully processed this key.
EFI_WARN_STALE_DATA	Successfully processed this key, however, the key’s parameters exceed internal policies/limits and should be replaced.
EFI_COMPROMISED_DATA	Successfully processed this key, but the key may have been compromised and must be replaced.
EFI_UNSUPPORTED	Key format is not supported by the service.
EFI_OUT_OF_RESOURCES	Could not allocate resources for the key processing.
EFI_TIMEOUT	Timed out waiting for device or key server.
EFI_DEVICE_ERROR	Device or key server error.
EFI_INVALID_PARAMETER	KeyFormat is invalid.
EFI_NOT_FOUND	The key does not exist on the KMS.

#define EFI_KMS_ATTRIBUTE_TYPE_NONE          0x00
#define EFI_KMS_ATTRIBUTE_TYPE_INTEGER       0x01
#define EFI_KMS_ATTRIBUTE_TYPE_LONG_INTEGER  0x02
#define EFI_KMS_ATTRIBUTE_TYPE_BIG_INTEGER   0x03
#define EFI_KMS_ATTRIBUTE_TYPE_ENUMERATION   0x04
#define EFI_KMS_ATTRIBUTE_TYPE_BOOLEAN       0x05
#define EFI_KMS_ATTRIBUTE_TYPE_BYTE_STRING   0x06
#define EFI_KMS_ATTRIBUTE_TYPE_TEXT_STRING   0x07
#define EFI_KMS_ATTRIBUTE_TYPE_DATE_TIME     0x08
#define EFI_KMS_ATTRIBUTE_TYPE_INTERVAL      0x09
#define EFI_KMS_ATTRIBUTE_TYPE_STRUCTURE     0x0A
#define EFI_KMS_ATTRIBUTE_TYPE_DYNAMIC       0x0B


typedef struct {
  UINT32                                 FieldCount;
  EFI_KMS_DYNAMIC_FIELD                  Field[1];
}   EFI_KMS_DYNAMIC_ATTRIBUTE;

FieldCount: The number of members in the EFI_KMS_DYNAMIC_ATTRIBUTE structure.
Field: An array of EFI_KMS_DYNAMIC_FIELD structures.

typedef struct {
  UINT16         Tag;
  UINT16         Type;
  UINT32         Length;
  UINT8          KeyAttributeData[1];
}   EFI_KMS_DYNAMIC_FIELD;

Tag: Part of a tag-type-length triplet that identifies the KeyAttributeData formatting. The definition of the value is outside the scope of this standard and may be defined by the KMS.
Type: Part of a tag-type-length triplet that identifies the KeyAttributeData formatting. The definition of the value is outside the scope of this standard and may be defined by the KMS.
Length: Length in bytes of the KeyAttributeData.
KeyAttributeData: An array of bytes to hold the attribute data associated with the KeyAttributeIdentifier.

typedef struct {
  UINT8              KeyAttributeIdentifierType;
  UINT8              KeyAttributeIdentifierCount;
  VOID               *KeyAttributeIdentifier;
  UINT16             KeyAttributeInstance;
  UINT16             KeyAttributeType;
  UINT16             KeyAttributeValueSize;
  VOID               *KeyAttributeValue;
  EFI_STATUS         KeyAttributeStatus;
} EFI_KMS_KEY_ATTRIBUTE;

KeyAttributeIdentifierType: The data type used for the KeyAttributeIdentifier field. Values for this field are defined by the EFI_KMS_DATA_TYPE constants, except that EFI_KMS_DATA_TYPE_BINARY is not valid for this field.
KeyAttributeIdentifierCount: The length of the KeyAttributeIdentifier field in units defined by KeyAttributeIdentifierType field. This field is limited to the range 0 to 255.
KeyAttributeIdentifier: Pointer to an array of KeyAttributeIdentifierType elements. For string types, there must not be a null-termination element at the end of the array.
KeyAttributeInstance: The instance number of this attribute. If there is only one instance, the value is set to one. If this value is set to 0xFFFF (all binary 1’s) then this field should be ignored if an output or treated as a wild card matching any value if it is an input. If the attribute is stored with this field, it will match any attribute request regardless of the setting of the field in the request. If set to 0xFFFF in the request, it will match any attribute with the same KeyAttributeIdentifier.
KeyAttributeType: The data type of the KeyAttributeValue (e.g. struct, bool, etc.). See the list of KeyAttributeType definitions.
KeyAttributeValueSize: The size in bytes of the KeyAttribute field. A value of zero for this field indicates that no key attribute value is available.
KeyAttributeValue: Pointer to a key attribute value for the attribute specified by the KeyAttributeIdentifier field. If the KeyAttributeValueSize field is zero, then this field must be NULL.
KeyAttributeStatus: Specifies the results of KMS operations performed with this attribute. This field is used to indicate the status of individual operations when a KMS function is called with multiple EFI_KMS_KEY_ATTRIBUTE structures. KeyAttributeStatus codes returned for the individual key attribute requests are:

Status Codes Returned

EFI_SUCCESS	Successfully processed this request.
EFI_WARN_STALE_DATA	Successfully processed this request, however, the key’s parameters exceed internal policies/limits and should be replaced.
EFI_COMPROMISED_DATA	Successfully processed this request, but the key may have been compromised and must be replaced.
EFI_UNSUPPORTED	Key attribute format is not supported by the service.
EFI_OUT_OF_RESOURCES	Could not allocate resources for the request processing.
EFI_TIMEOUT	Timed out waiting for device or key server.
EFI_DEVICE_ERROR	Device or key server error.
EFI_INVALID_PARAMETER	A field in the EFI_KMS_KEY_ATTRIBUTE structure is invalid.
EFI_NOT_FOUND	The key attribute does not exist on the KMS.

Description

The EFI_KMS_SERVICE_PROTOCOL defines a UEFI protocol that can be used by UEFI drivers and applications to access cryptographic keys associated with their operation that are stored and possibly managed by a remote key management service (KMS). For example, a storage device driver may require a set of one or more keys to enable access to regions on the storage devices that it manages.

The protocol can be used to request the generation of new keys from the KMS, to register locally generated keys with the KMS, to retrieve existing keys from the KMS, and to delete obsolete keys from the KMS. It also allows the device driver to manage attributes associated with individual keys on the KMS, and to retrieve keys based on those attributes.

A platform implementing this protocol may use internal or external key servers to provide the functionality required by this protocol. For external servers, the protocol implementation is expected to supply and maintain the connection parameters required to connect and authenticate to the remote server. The connection may be made during the initial installation of the protocol, or it may be delayed until the first GetServiceStatus() request is received.

Each client using the KMS protocol may identify itself to the protocol implementation using a EFI_KMS_CLIENT_INFO structure. If the KMS supported by this protocol requires the client to provide a client identifier, then this structure must be provided on all function calls.

While this protocol is intended to abstract the functions associated with storing and managing keys so that the protocol user does not have to be aware of the specific KMS providing the service, it can also be used by callers which must interact directly with a specific KMS. For these users, the protocol manages the connection to the KMS while the user controls the operational interface via a client data pass thru function.

The EFI_KMS_SERVICE_PROTOCOL provides the capability for the caller to pass arbitrary data to the KMS or to receive such data back from the KMS via parameters on most functions. The use of such data is at the discretion of the caller, but it should only be used sparingly as it reduces the interoperability of the caller’s software.

37.3.2. EFI_KMS_PROTOCOL.GetServiceStatus()

Summary

Get the current status of the key management service.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_KMS_GET_SERVICE_STATUS) (
  IN EFI_KMS_PROTOCOL             *This
  );

Parameters

This: Pointer to the EFI_KEY_MANAGEMENT_SERVICE_PROTOCOL instance.

Description

The GetServiceStatus() function allows the user to query the current status of the KMS and should be called before attempting any operations to the KMS. If the protocol has not been marked as available, then the user must call this function to attempt to initiate the connection to the KMS as it may have been deferred to the first user by the system firmware.

If the connection to the KMS has not yet been established by the system firmware, then this function will attempt to establish the connection, update the protocol structure content as appropriate, and mark the service as available.

Status Codes Returned

EFI_SUCCESS	The KMS is ready for use.
EFI_NOT_READY	No connection to the KMS is available.
EFI_NO_MAPPING	No valid connection configuration exists for the KMS.
EFI_NO_RESPONSE	No response was received from the KMS.
EFI_DEVICE_ERROR	An error occurred when attempting to access the KMS.
EFI_INVALID_PARAMETER	This is NULL.

37.3.2.1. EFI_KMS_PROTOCOL.RegisterClient()

Summary

Register client information with the supported KMS.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_KMS_REGISTER_CLIENT) (
  IN    EFI_KMS_PROTOCOL            *This,
  IN    EFI_KMS_CLIENT_INFO         *Client,
  IN OUT UINTN                      *ClientDataSize OPTIONAL,
  IN OUT VOID                       **ClientData OPTIONAL
  );

Parameters

This: Pointer to the EFI_KEY_MANAGEMENT_SERVICE_PROTOCOL instance.
Client: Pointer to a valid EFI_KMS_CLIENT_INFO structure.
ClientDataSize: Pointer to the size, in bytes, of an arbitrary block of data specified by the ClientData parameter. This parameter may be NULL, in which case the ClientData parameter will be ignored and no data will be transferred to or from the KMS. If the parameter is not NULL, then ClientData must be a valid pointer. If the value pointed to is 0, no data will be transferred to the KMS, but data may be returned by the KMS. For all non-zero values ClientData will be transferred to the KMS, which may also return data to the caller. In all cases, the value upon return to the caller will be the size of the data block returned to the caller, which will be zero if no data is returned from the KMS.
ClientData: Pointer to a pointer to an arbitrary block of data of ClientDataSize that is to be passed directly to the KMS if it supports the use of client data. This parameter may be NULL if and only if the ClientDataSize parameter is also NULL. Upon return to the caller, ClientData points to a block of data of * *ClientDataSize that was returned from the KMS. If the returned value for ClientDataSize is zero, then the returned value for ClientData must be NULL and should be ignored by the caller. The KMS protocol consumer is responsible for freeing all valid buffers used for client data regardless of whether they are allocated by the caller for input to the function or by the implementation for output back to the caller.

Description

The RegisterClient() function registers client information with the KMS using a EFI_KMS_CLIENT_INFO structure.

There are two methods of handling client information. The caller may supply a client identifier in the EFI_KMS_CLIENT_INFO structure prior to making the call along with an optional name string. The client identifier will be passed on to the KMS if it supports client identifiers. If the KMS accepts the client id, then the EFI_KMS_CLIENT_INFO structure will be returned to the caller unchanged. If the KMS does not accept the client id, it may simply reject the request, or it may supply an alternate identifier of its own,

The caller may also request a client identifier from the KMS by passing NULL values in the EFI_KMS_CLIENT_INFO structure. If the KMS supports this action, it will generate the identifier and return it in the structure. Otherwise, the implementation may generate a unique identifier, returning it in the structure, or it may indicate that the function is unsupported.

The ClientDataSize and ClientData parameters allow the caller to pass an arbitrary block of data to/from the KMS for uses such as auditing or access control. The KMS protocol implementation does not alter this data block other than to package it for transmission to the KMS. The use of these parameters is optional.

Status Codes Returned

EFI_SUCCESS	The client information has been accepted by the KMS.
EFI_NOT_READY	No connection to the KMS is available.
EFI_NO_RESPONSE	There was no response from the device or the key server.
EFI_ACCESS_DENIED	Access was denied by the device or the key server.
EFI_DEVICE_ERROR	An error occurred when attempting to access the KMS.
EFI_OUT_OF_RESOURCES	Required resources were not available to perform the function.
EFI_INVALID_PARAMETER	This is NULL.
EFI_UNSUPPORTED	The KMS does not support the use of client identifiers.

37.3.2.2. EFI_KMS_PROTOCOL.CreateKey()

Summary

Request that the KMS generate one or more new keys and associate them with key identifiers. The key value(s) is returned to the caller.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_KMS_CREATE_KEY) (
  IN   EFI_KMS_PROTOCOL             *This,
  IN   EFI_KMS_CLIENT_INFO          *Client,
  IN OUT UINT16                     *KeyDescriptorCount,
  IN OUT EFI_KMS_KEY_DESCRIPTOR     *KeyDescriptors,
  IN OUT UINTN                      *ClientDataSize OPTIONAL,
  IN OUT VOID                       **ClientData OPTIONAL
  );

Parameters

This

Pointer to this EFI_KMS_PROTOCOL instance.

Client

Pointer to a valid EFI_KMS_CLIENT_INFO structure.

KeyDescriptorCount

Pointer to a count of the number of key descriptors to be processed by this operation. On return, this number will be updated with the number of key descriptors successfully processed.

KeyDescriptors

Pointer to an array of EFI_KMS_KEY_DESCRIPTOR structures which describe the keys to be generated.

On input, the KeyIdentifierSize and the KeyIdentifier may specify an identifier to be used for the key, but this is not required. The KeyFormat field must specify a key format GUID reported as supported by the KeyFormats field of the EFI_KMS_PROTOCOL. The value for this field in the first key descriptor will be considered the default value for subsequent key descriptors requested in this operation if those key descriptors have a NULL GUID in the key format field.

On output, the KeyIdentifierSize and KeyIdentifier fields will specify an identifier for the key which will be either the original identifier if one was provided, or an identifier generated either by the KMS or the KMS protocol implementation. The KeyFormat field will be updated with the GUID used to generate the key if it was a NULL GUID, and the KeyValue field will contain a pointer to memory containing the key value for the generated key. Memory for both the KeyIdentifier and the KeyValue fields will be allocated with the BOOT_SERVICES_DATA type and must be freed by the caller when it is no longer needed. Also, the KeyStatus field must reflect the result of the request relative to that key.

ClientDataSize

Pointer to the size, in bytes, of an arbitrary block of data specified by the ClientData parameter. This parameter may be NULL in which case the ClientData parameter will be ignored and no data will be transferred to or from the KMS. If the parameter is not NULL, then ClientData must be a valid pointer. If the value pointed to is 0, no data will be transferred to the KMS, but data may be returned by the KMS. For all non-zero values ClientData will be transferred to the KMS, which may also return data to the caller. In all cases, the value upon return to the caller will be the size of the data block returned to the caller, which will be zero if no data is returned from the KMS.

ClientData

Pointer to a pointer to an arbitrary block of data of * ClientDataSize that is to be passed directly to the KMS if it supports the use of client data. This parameter may be NULL if and only if the ClientDataSize parameter is also NULL. Upon return to the caller, * ClientData points to a block of data of * ClientDataSize that was returned from the KMS. If the returned value for * ClientDataSize is zero, then the returned value for * ClientData must be NULL and should be ignored by the caller. The KMS protocol consumer is responsible for freeing all valid buffers used for client data regardless of whether they are allocated by the caller for input to the function or by the implementation for output back to the caller.

Description

The CreateKey() method requests the generation of one or more new keys, and key identifier and key values are returned to the caller. The support of this function is optional as some key servers do not provide a key generation capability.

The Client parameter identifies the caller to the key management service. This identifier may be used for auditing or access control. This parameter is optional unless the KMS requires a client identifier in order to perform the requested action.

The KeyDescriptorCount and KeyDescriptors parameters are used to specify the key algorithm, size, and attributes for the requested keys. Any number of keys may be requested in a single operation, regardless of whether the KMS supports multiple key definitions in a single request or not. The KMS protocol implementation is responsible for generating the appropriate requests (single/multiple) to the KMS.

The ClientDataSize and ClientData parameters allow the caller to pass an arbitrary block of data to/from the KMS for uses such as auditing or access control. The KMS protocol implementation does not alter this data block other than to package it for transmission to the KMS. The use of these parameters is optional.

Status Codes Returned

The CreateKey() function will return a status which indicates the overall status of the request. Note that this may be different from the status reported for individual key requests.

EFI_SUCCESS	Successfully generated and retrieved all requested keys.
EFI_UNSUPPORTED	This function is not supported by the KMS. –OR– One (or more) of the key requests submitted is not supported by the KMS. Check individual key request(s) to see which ones may have been processed.
EFI_OUT_OF_RESOURCES	Required resources were not available for the operation.
EFI_TIMEOUT	Timed out waiting for device or key server. Check individual key request(s) to see which ones may have been processed.
EFI_ACCESS_DENIED	Access was denied by the device or the key server; OR a ClientId is required by the server and either no id was provided or an invalid id was provided
EFI_DEVICE_ERROR	An error occurred when attempting to access the KMS. Check individual key request(s) to see which ones may have been processed.
EFI_INVALID_PARAMETER	This is NULL, ClientId is required but it is NULL , KeyDescriptorCount is NULL, or Keys is NULL
EFI_NOT_FOUND	One or more EFI_KMS_KEY_DESCRIPTOR structures could not be processed properly. KeyDescriptorCount contains the number of structures which were successfully processed. Individual structures will reflect the status of the processing for that structure.

37.3.2.3. EFI_KMS_PROTOCOL.GetKey()

Summary

Retrieve an existing key.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_KMS_GET_KEY) (
  IN   EFI_KMS_PROTOCOL             *This,
  IN   EFI_KMS_CLIENT_INFO          *Client,
  IN OUT UINT16                     *KeyDescriptorCount,
  IN OUT EFI_KMS_KEY_DESCRIPTOR     *KeyDescriptors,
  IN OUT UINTN                      *ClientDataSize OPTIONAL,
  IN OUT VOID                       **ClientData OPTIONAL
  );

Parameters

This: Pointer to this EFI_KMS_PROTOCOL instance.
Client: Pointer to a valid EFI_KMS_CLIENT_INFO structure.
KeyDescriptorCount: Pointer to a count of the number of keys to be processed by this operation. On return, this number will be updated with number of keys successfully processed.
KeyDescriptors: Pointer to an array of EFI_KMS_KEY_DESCRIPTOR structures which describe the keys to be retrieved from the KMS. On input, the KeyIdentifierSize and the KeyIdentifier must specify an identifier to be used to retrieve a specific key. All other fields in the descriptor should be NULL . On output, the KeyIdentifierSize and KeyIdentifier fields will be unchanged, while the KeyFormat and KeyValue fields will be updated values associated with this key identifier. Memory for the KeyValue field will be allocated with the BOOT_SERVICES_DATA type and must be freed by the caller when it is no longer needed. Also, the KeyStatus field will reflect the result of the request relative to the individual key descriptor.
ClientDataSize: Pointer to the size, in bytes, of an arbitrary block of data specified by the ClientData parameter. This parameter may be NULL in which case the ClientData parameter will be ignored and no data will be transferred to or from the KMS. If the parameter is not NULL, then ClientData must be a valid pointer. If the value pointed to is 0, no data will be transferred to the KMS, but data may be returned by the KMS. For all non-zero values **ClientData* will be transferred to the KMS, which may also return data to the caller. In all cases, the value upon return to the caller will be the size of the data block returned to the caller, which will be zero if no data is returned from the KMS.
ClientData: Pointer to a pointer to an arbitrary block of data of * ClientDataSize that is to be passed directly to the KMS if it supports the use of client data. This parameter may be NULL if and only if the ClientDataSize parameter is also NULL. Upon return to the caller, * ClientData points to a block of data of * ClientDataSize that was returned from the KMS. If the returned value for **ClientDataSize* is zero, then the returned value for **ClientData* must be NULL and should be ignored by the caller. The KMS protocol consumer is responsible for freeing all valid buffers used for client data regardless of whether they are allocated by the caller for input to the function or by the implementation for output back to the caller.

Description

The GetKey() function retrieves one or more existing keys from the KMS and returns the key values to the caller. This function must be supported by every KMS protocol instance.

The Client parameter identifies the caller to the key management service. It may be used for auditing or access control. The use of this parameter is optional unless the KMS requires it in order to perform the requested action.

The KeyDescriptorCount and KeyDescriptors parameters are used to specify the identifier(s) to be used to retrieve the key values, which will be returned in the KeyFormat and KeyValue fields of each EFI_KMS_KEY_DESCRIPTOR structure. Any number of keys may be requested in a single operation, regardless of whether the KMS supports multiple key definitions in a single request or not. The KMS protocol implementation is responsible for generating the appropriate requests (single/multiple) to the KMS.

The ClientDataSize and ClientData parameters allow the caller to pass an arbitrary block of data to/from the KMS for uses such as auditing or access control. The KMS protocol implementation does not alter this data block other than to package it for transmission to the KMS. The use of these parameters is optional.

Status Codes Returned

The GetKey() function will return a status which indicates the overall status of the request. Note that this may be different from the status reported for individual key requests.

EFI_SUCCESS	Successfully retrieved all requested keys.
EFI_OUT_OF_RESOURCES	Could not allocate resources for the method processing.
EFI_TIMEOUT	Timed out waiting for device or key server. Check individual key request(s) to see which ones may have been processed.
EFI_BUFFER_TOO_SMALL	If multiple keys are associated with a single identifier, and the KeyValue buffer does not contain enough structures ( KeyDescriptorCount ) to contain all the key data, then the available structures will be filled and KeyDescriptorCount will be updated to indicate the number of keys which could not be processed.
EFI_ACCESS_DENIED	Access was denied by the device or the key server; OR a ClientId is required by the server and either none or an invalid id was provided
EFI_DEVICE_ERROR	Device or key server error. Check individual key request(s) to see which ones may have been processed.
EFI_INVALID_PARAMETER	This is NULL, ClientId is required but it is NULL , KeyDescriptorCount is NULL, or Keys is NULL
EFI_NOT_FOUND	One or more EFI_KMS_KEY_DESCRIPTOR structures could not be processed properly. KeyDescriptorCount contains the number of structures which were successfully processed. Individual structures will reflect the status of the processing for that structure.
EFI_UNSUPPORTED	The implementation/KMS does not support this function

37.3.2.4. EFI_KMS_PROTOCOL.AddKey()

Summary

Add a new key.

Prototype

typedef
  EFI_STATUS
  (EFIAPI *EFI_KMS_ADD_KEY) (
    IN    EFI_KMS_PROTOCOL               *This,
    IN    EFI_KMS_CLIENT_INFO            *Client,
    IN OUT UINT16                        *KeyDescriptorCount,
    IN OUT EFI_KMS_KEY_DESCRIPTOR        *KeyDescriptors,
    IN OUT UINTN                         *ClientDataSize OPTIONAL,
    IN OUT VOID                          **ClientData OPTIONAL
    );

Parameters

This: Pointer to this EFI_KMS_PROTOCOL instance.
Client: Pointer to a valid EFI_KMS_CLIENT_INFO structure.
KeyDescriptorCount: Pointer to a count of the number of keys to be processed by this operation. On normal returns, this number will be updated with number of keys successfully processed.
KeyDescriptors: Pointer to an array of EFI_KMS_KEY_DESCRIPTOR structures which describe the keys to be added. On input, the KeyId field for first key must contain valid identifier data to be used for adding a key to the KMS. The values for these fields in this key definition will be considered default values for subsequent keys requested in this operation. A value of 0 in any subsequent KeyId field will be replaced with the current default value. The KeyFormat and KeyValue fields for each key to be added must contain consistent values to be associated with the given KeyId. On return, the KeyStatus field will reflect the result of the operation for each key request.
ClientDataSize: Pointer to the size, in bytes, of an arbitrary block of data specified by the ClientData parameter. This parameter may be NULL, in which case the ClientData parameter will be ignored and no data will be transferred to or from the KMS. If the parameter is not NULL, then ClientData must be a valid pointer. If the value pointed to is 0, no data will be transferred to the KMS, but data may be returned by the KMS. For all non-zero values **ClientData* will be transferred to the KMS, which may also return data to the caller. In all cases, the value upon return to the caller will be the size of the data block returned to the caller, which will be zero if no data is returned from the KMS.
ClientData: Pointer to a pointer to an arbitrary block of data of **ClientDataSize* that is to be passed directly to the KMS if it supports the use of client data. This parameter may be NULL if and only if the ClientDataSize parameter is also NULL. Upon return to the caller, **ClientData* points to a block of data of **ClientDataSize* that was returned from the KMS. If the returned value for **ClientDataSize* is zero, then the returned value for **ClientData* must be NULL and should be ignored by the caller. The KMS protocol consumer is responsible for freeing all valid buffers used for client data regardless of whether they are allocated by the caller for input to the function or by the implementation for output back to the caller.

Description

The AddKey() function registers a new key with the key management service. The support for this method is optional, as not all key servers support importing keys from clients.

The Client parameter identifies the caller to the key management service. It may be used for auditing or access control. The use of this parameter is optional unless the KMS requires it in order to perform the requested action.

The KeyDescriptorCount and KeyDescriptors parameters are used to specify the key identifier, key format and key data to be registered on the. Any number of keys may be registered in a single operation, regardless of whether the KMS supports multiple key definitions in a single request or not. The KMS protocol implementation is responsible for generating the appropriate requests (single/multiple) to the KMS.

The ClientDataSize and ClientData parameters allow the caller to pass an arbitrary block of data to/from the KMS for uses such as auditing or access control. The KMS protocol implementation does not alter this data block other than to package it for transmission to the KMS. The use of these parameters is optional.

Status Codes Returned

The AddKey() function will return a status which indicates the overall status of the request. Note that this may be different from the status reported for individual key requests.

EFI_SUCCESS	Successfully added all requested keys.
EFI_OUT_OF_RESOURCES	Could not allocate required resources.
EFI_TIMEOUT	Timed out waiting for device or key server. Check individual key request(s) to see which ones may have been processed.
EFI_BUFFER_TOO_SMALL	If multiple keys are associated with a single identifier, and the KeyValue buffer does not contain enough structures ( KeyDescriptorCount ) to contain all the key data, then the available structures will be filled and KeyDescriptorCount will be updated to indicate the number of keys which could not be processed.
EFI_ACCESS_DENIED	Access was denied by the device or the key server; OR a ClientId is required by the server and either none or an invalid id was provided
EFI_DEVICE_ERROR	Device or key server error. Check individual key request(s) to see which ones may have been processed.
EFI_INVALID_PARAMETER	This is NULL, ClientId is required but it is NULL ,KeyDescriptorCount is NULL, or Keys is NULL
EFI_NOT_FOUND	One or more EFI_KMS_KEY_DESCRIPTOR structures could not be processed properly. KeyDescriptorCount contains the number of structures which were successfully processed. Individual structures will reflect the status of the processing for that structure.
EFI_UNSUPPORTED	The implementation/KMS does not support this function

37.3.2.5. EFI_KMS_PROTOCOL.DeleteKey()

Summary

Delete an existing key from the KMS database.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_KMS_DELETE_KEY) (
  IN    EFI_KMS_PROTOCOL                  *This,
  IN EFI_KMS_CLIENT_INFO                  *Client,
  IN OUT UINT16                           *KeyDescriptorCount,
  IN OUT EFI_KMS_KEY_DESCRIPTOR           *KeyDescriptors,
  IN OUT UINTN                            *ClientDataSize OPTIONAL,
  IN OUT VOID                             **ClientData OPTIONAL
  );

Parameters

This: Pointer to this EFI_KMS_PROTOCOL instance.
Client: Pointer to a valid EFI_KMS_CLIENT_INFO structure.
KeyDescriptorCount: Pointer to a count of the number of keys to be processed by this operation. On normal returns, this number will be updated with number of keys successfully processed.
KeyDescriptors: Pointer to an array of EFI_KMS_KEY_DESCRIPTOR structures which describe the keys to be deleted. On input, the KeyId field for first key must contain valid identifier data to be used for adding a key to the KMS. The values for these fields in this key definition will be considered default values for subsequent keys requested in this operation. A value of 0 in any subsequent KeyId field will be replaced with the current default value. The KeyFormat and KeyValue fields are ignored, but should be 0. On return, the KeyStatus field will reflect the result of the operation for each key request.
ClientDataSize: Pointer to the size, in bytes, of an arbitrary block of data specified by the ClientData parameter. This parameter may be NULL, in which case the ClientData parameter will be ignored and no data will be transferred to or from the KMS. If the parameter is not NULL, then ClientData must be a valid pointer. If the value pointed to is 0, no data will be transferred to the KMS, but data may be returned by the KMS. For all non-zero values **ClientData* will be transferred to the KMS, which may also return data to the caller. In all cases, the value upon return to the caller will be the size of the data block returned to the caller, which will be zero if no data is returned from the KMS.
ClientData: Pointer to a pointer to an arbitrary block of data of **ClientDataSize* that is to be passed directly to the KMS if it supports the use of client data. This parameter may be NULL if and only if the ClientDataSize parameter is also NULL. Upon return to the caller, **ClientData* points to a block of data of **ClientDataSize* that was returned from the KMS. If the returned value for **ClientDataSize* is zero, then the returned value for **ClientData* must be NULL and should be ignored by the caller. The KMS protocol consumer is responsible for freeing all valid buffers used for client data regardless of whether they are allocated by the caller for input to the function or by the implementation for output back to the caller.

Description

The DeleteKey() function deregisters an existing key from the device or KMS. The support for this method is optional, as not all key servers support deleting keys from clients.

The Client parameter identifies the caller to the key management service. It may be used for auditing or access control. The use of this parameter is optional unless the KMS requires it in order to perform the requested action.

The KeyDescriptorCount and KeyDescriptors parameters are used to specify the key identifier(s) for the keys to be deleted. Any number of keys may be deleted in a single operation, regardless of whether the KMS supports multiple key definitions in a single request or not. The KMS protocol implementation is responsible for generating the appropriate requests (single/multiple) to the KMS.

The ClientDataSize and ClientData parameters allow the caller to pass an arbitrary block of data to/from the KMS for uses such as auditing or access control. The KMS protocol implementation does not alter this data block other than to package it for transmission to the KMS. The use of these parameters is optional.

Status Codes Returned

The DeleteKey() function will return a status which indicates the overall status of the request. Note that this may be different from the status reported for individual key requests.

EFI_SUCCESS	Successfully deleted all requested keys.
EFI_OUT_OF_RESOURCES	Could not allocate required resources.
EFI_TIMEOUT	Timed out waiting for device or key server. Check individual key request(s) to see which ones may have been processed.
EFI_ACCESS_DENIED	Access was denied by the device or the key server; OR a ClientId is required by the server and either none or an invalid id was provided
EFI_DEVICE_ERROR	Device or key server error. Check individual key request(s) to see which ones may have been processed.
EFI_INVALID_PARAMETER	This is NULL, ClientId is required but it is NULL, KeyDescriptorCount is NULL, or Keys is NULL
EFI_NOT_FOUND	One or more EFI_KMS_KEY_DESCRIPTOR structures could not be processed properly. KeyDescriptorCount contains the number of structures which were successfully processed. Individual structures will reflect the status of the processing for that structure.
EFI_UNSUPPORTED	The implementation/KMS does not support this function

37.3.2.6. EFI_KMS_PROTOCOL.GetKeyAttributes()

Summary

Get one or more attributes associated with a specified key identifier. If none are found, the returned attributes count contains a value of zero.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_KMS_GET_KEY_ATTRIBUTES) (
  IN  EFI_KMS_PROTOCOL                  *This,
  IN  EFI_KMS_CLIENT_INFO               *Client,
  IN  UINT8                             *KeyIdentifierSize,
  IN  CONST VOID                        *KeyIdentifier,
  IN OUT UINT16                         *KeyAttributesCount,
  IN OUT EFI_KMS_KEY_ATTRIBUTE          *KeyAttributes,
  IN OUT UINTN                          *ClientDataSize OPTIONAL,
  IN OUT VOID                           **ClientData OPTIONAL
  );

Parameters

This: Pointer to this EFI_KMS_PROTOCOL instance.
Client: Pointer to a valid EFI_KMS_CLIENT_INFO structure.
KeyIdentifierSize: Pointer to the size in bytes of the KeyIdentifier variable.
KeyIdentifier: Pointer to the key identifier associated with this key.
KeyAttributesCount: Pointer to the number of EFI_KMS_KEY_ATTRIBUTE structures associated with the Key identifier. If none are found, the count value is zero on return. On input this value reflects the number of KeyAttributes that may be returned. On output, the value reflects the number of completed KeyAttributes structures found.
KeyAttributes: Pointer to an array of EFI_KMS_KEY_ATTRIBUTE structures associated with the Key Identifier. On input, the fields in the structure should be NULL. On output, the attribute fields will have updated values for attributes associated with this key identifier.
ClientDataSize: Pointer to the size, in bytes, of an arbitrary block of data specified by the ClientData parameter. This parameter may be NULL, in which case the ClientData parameter will be ignored and no data will be transferred to or from the KMS. If the parameter is not NULL, then ClientData must be a valid pointer. If the value pointed to is 0, no data will be transferred to the KMS, but data may be returned by the KMS. For all non-zero values * ClientData will be transferred to the KMS, which may also return data to the caller. In all cases, the value upon return to the caller will be the size of the data block returned to the caller, which will be zero if no data is returned from the KMS.
ClientData: Pointer to a pointer to an arbitrary block of data of * ClientDataSize that is to be passed directly to the KMS if it supports the use of client data. This parameter may be NULL if and only if the ClientDataSize parameter is also NULL. Upon return to the caller, * ClientData points to a block of data of * ClientDataSize that was returned from the KMS. If the returned value for * ClientDataSize is zero, then the returned value for * ClientData must be NULL and should be ignored by the caller. The KMS protocol consumer is responsible for freeing all valid buffers used for client data regardless of whether they are allocated by the caller for input to the function or by the implementation for output back to the caller.

Description

The GetKeyAttributes() function returns one or more attributes for a key.

The ClientIdentifierSize and ClientIdentifier parameters identify the caller to the key management service. It may be used for auditing or access control. The use of this parameter is optional unless the KMS requires it in order to perform the requested action.

The KeyIdentifierSize and KeyIdentifier parameters identify the key whose attributes are to be returned by the key management service. They may be used to retrieve additional information about a key, whose format is defined by the KeyAttribute. Attributes returned may be of the same or different names.

The ClientDataSize and ClientData parameters allow the caller to pass an arbitrary block of data to/from the KMS for uses such as auditing or access control. The KMS protocol implementation does not alter this data block other than to package it for transmission to the KMS. The use of these parameters is optional unless the KMS requires it in order to perform the requested action.

Status Codes Returned

The GetKeyAttributes() function will return a status which indicates the overall status of the request. Note that this may be different from the status reported for individual key attribute requests.

EFI_SUCCESS	Successfully retrieved all key attributes.
EFI_OUT_OF_RESOURCES	Could not allocate resources for the method processing.
EFI_TIMEOUT	Timed out waiting for device or key server. Check individual key attribute request(s) to see which ones may have been processed.
EFI_BUFFER_TOO_SMALL	If multiple key attributes are associated with a single identifier, and the KeyAttributes buffer does not contain enough structures ( KeyAttributesCount ) to contain all the key attributes data, then the available structures will be filled and KeyAttributesCount will be updated to indicate the number of key attributes which could not be processed.
EFI_ACCESS_DENIED	Access was denied by the device or the key server; OR a ClientId is required by the server and either none or an invalid id was provided
EFI_DEVICE_ERROR	Device or key server error. Check individual key attribute request(s) (i.e., key attribute status for each) to see which ones may have been processed.
EFI_INVALID_PARAMETER	This is NULL, ClientId is required but it is NULL, KeyIdentifierSize is NULL, or KeyIdentifier is NULL, or KeyAttributes is NULL, or KeyAttributesSize is NULL.
EFI_NOT_FOUND	The KeyIdentifier could not be found. KeyAttributesCount contains zero. Individual structures will reflect the status of the processing for that structure.
EFI_UNSUPPORTED	The implementation/KMS does not support this function

37.3.2.7. EFI_KMS_PROTOCOL.AddKeyAttributes()

Summary

Add one or more attributes to a key specified by a key identifier.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_KMS_ADD_KEY_ATTRIBUTES) (
  IN   EFI_KMS_PROTOCOL                   *This,
  IN   EFI_KMS_CLIENT_INFO                *Client,
  IN   UINT                               *KeyIdentifierSize,
  IN   CONST VOID                         *KeyIdentifier,
  IN OUT UINT16                           *KeyAttributesCount,
  IN OUT EFI_KMS_KEY_ATTRIBUTE            *KeyAttributes,
  IN OUT UINTN                            *ClientDataSize OPTIONAL,
  IN OUT VOID                             **ClientData OPTIONAL
  );

Parameters

This: Pointer to this EFI_KMS_PROTOCOL instance.
Client: Pointer to a valid EFI_KMS_CLIENT_INFO structure.
KeyIdentifierSize: Pointer to the size in bytes of the KeyIdentifier variable.
KeyIdentifier: Pointer to the key identifier associated with this key.
KeyAttributesCount: Pointer to the number of EFI_KMS_KEY_ATTRIBUTE structures to associate with the Key. On normal returns, this number will be updated with the number of key attributes successfully processed.
KeyAttributes: Pointer to an array of EFI_KMS_KEY_ATTRIBUTE structures providing the attribute information to associate with the key. On input, the values for the fields in the structure are completely filled in. On return the KeyAttributeStatus field will reflect the result of the operation for each key attribute request.
ClientDataSize: Pointer to the size, in bytes, of an arbitrary block of data specified by the ClientData parameter. This parameter may be NULL, in which case the ClientData parameter will be ignored and no data will be transferred to or from the KMS. If the parameter is not NULL, then ClientData must be a valid pointer. If the value pointed to is 0, no data will be transferred to the KMS, but data may be returned by the KMS. For all non-zero values * ClientData will be transferred to the KMS, which may also return data to the caller. In all cases, the value upon return to the caller will be the size of the data block returned to the caller, which will be zero if no data is returned from the KMS.
ClientData: Pointer to a pointer to an arbitrary block of data of * ClientDataSize that is to be passed directly to the KMS if it supports the use of client data. This parameter may be NULL if and only if the ClientDataSize parameter is also NULL. Upon return to the caller, * ClientData points to a block of data of * ClientDataSize that was returned from the KMS. If the returned value for * ClientDataSize is zero, then the returned value for * ClientData must be NULL and should be ignored by the caller. The KMS protocol consumer is responsible for freeing all valid buffers used for client data regardless of whether they are allocated by the caller for input to the function or by the implementation for output back to the caller.

Description

The AddKeyAttributes() function adds one or more key attributes. If this function is not supported by a KMS protocol instance then it is assumed that there is an alternative means available for attribute management in the KMS.

The Client parameters identify the caller to the key management service. It may be used for auditing or access control. The use of this parameter is optional unless the KMS requires it in order to perform the requested action.

The KeyIdentifierSize and KeyIdentifier parameters identify the key whose attributes are to be modified by the key management service

The KeyAttributesCount and KeyAttributes parameters are used to specify the key attributes data to be registered on the KMS. Any number of attributes may be registered in a single operation, regardless of whether the KMS supports multiple key attribute definitions in a single request or not. The KMS protocol implementation is responsible for generating the appropriate requests (single/multiple) to the KMS. In certain error situations, the status of each attribute is updated indicating if that attribute was successfully registered or not.

The ClientDataSize and ClientData parameters allow the caller to pass an arbitrary block of data to/from the KMS for uses such as auditing or access control. The KMS protocol implementation does not alter this data block other than to package it for transmission to the KMS. The use of these parameters is optional unless the KMS requires it in order to perform the requested action.

Status Codes Returned

The AddKeyAttributes() function will return a status which indicates the overall status of the request. Note that this may be different from the status reported for individual key attribute requests. Status codes returned for AddKeyAttributes() are:

EFI_SUCCESS	Successfully added all requested key attributes.
EFI_OUT_OF_RESOURCES	Could not allocate required resources.
EFI_TIMEOUT	Timed out waiting for device or key server. Check individual key attribute request(s) to see which ones may have been processed.
EFI_BUFFER_TOO_SMALL	If multiple keys attributes are associated with a single key identifier, and the attributes buffer does not contain enough structures ( KeyAttributesCount ) to contain all the data, then the available structures will be filled and KeyAttributesCount will be updated to indicate the number of key attributes which could not be processed. The status of each key attribute is also updated indicating success or failure for that attribute in case there are other errors for those attributes that could be processed.
EFI_ACCESS_DENIED	Access was denied by the device or the key server; OR a ClientId is required by the server and either none or an invalid id was provided
EFI_DEVICE_ERROR	Device or key server error. Check individual key attribute request(s) (i.e., key attribute status for each) to see which ones may have been processed.
EFI_INVALID_PARAMETER	This is NULL, ClientId is required but it is NULL, KeyAttributesCount is NULL, or KeyAttributes is NULL, or KeyIdentifierSize is NULL, or KeyIdentifer is NULL.
EFI_NOT_FOUND	The KeyIdentifier could not be found. On return the KeyAttributesCount contains the number of attributes processed. Individual structures will reflect the status of the processing for that structure.
EFI_UNSUPPORTED	The implementation/KMS does not support this function

37.3.2.8. EFI_KMS_PROTOCOL.DeleteKeyAttributes()

Summary

Delete attributes to a key specified by a key identifier.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_KMS_DELETE_KEY_ATTRIBUTES) (
  IN   EFI_KMS_PROTOCOL                *This,
  IN   EFI_KMS_CLIENT_INFO             *Client,
  IN   UINT8                           *KeyIdentifierSize,
  IN   CONST VOID                      *KeyIdentifier,
  IN OUT UINT16                        *KeyAttributesCount,
  IN OUT EFI_KMS_KEY_ATTRIBUTE         *KeyAttributes,
  IN OUT UINTN                         *ClientDataSize OPTIONAL,
  IN OUT VOI                           **ClientData OPTIONAL
  );

Parameters

This: Pointer to this EFI_KMS_PROTOCOL instance.
Client: Pointer to a valid EFI_KMS_CLIENT_INFO structure.
KeyIdentifierSize: Pointer to the size in bytes of the KeyIdentifier variable.
KeyIdentifier: Pointer to the key identifier associated with this key.
KeyAttributesCount: Pointer to the number of EFI_KMS_KEY_ATTRIBUTE structures associated with the Key. On input, the count value is one or more. On normal returns, this number will be updated with the number of key attributes successfully processed.
KeyAttributes: Pointer to an array of EFI_KMS_KEY_ATTRIBUTE structures associated with the key. On input, the values for the fields in the structure are completely filled in. On return the* KeyAttributeStatus field will reflect the result of the operation for each key attribute request.
ClientDataSize: Pointer to the size, in bytes, of an arbitrary block of data specified by the ClientData parameter. This parameter may be NULL, in which case the ClientData parameter will be ignored and no data will be transferred to or from the KMS. If the parameter is not NULL, then ClientData must be a valid pointer. If the value pointed to is 0, no data will be transferred to the KMS, but data may be returned by the KMS. For all non-zero values * ClientData will be transferred to the KMS, which may also return data to the caller. In all cases, the value upon return to the caller will be the size of the data block returned to the caller, which will be zero if no data is returned from the KMS.
ClientData: Pointer to a pointer to an arbitrary block of data of * ClientDataSize that is to be passed directly to the KMS if it supports the use of client data. This parameter may be NULL if and only if the ClientDataSize parameter is also NULL. Upon return to the caller, * ClientData points to a block of data of * ClientDataSize that was returned from the KMS. If the returned value for ClientDataSize is zero, then the returned value for * *ClientData must be NULL and should be ignored by the caller. The KMS protocol consumer is responsible for freeing all valid buffers used for client data regardless of whether they are allocated by the caller for input to the function or by the implementation for output back to the caller.

Description

The DeleteKeyAttributes() function removes key attributes for a key with the key management service.

The Client parameter identifies the caller to the key management service. It may be used for auditing or access control. The use of this parameter is optional unless the KMS requires it in order to perform the requested action.

The KeyIdentifierSize and KeyIdentifier parameters identify the key whose attributes are to be modified by the key management service

The KeyAttributesCount and KeyAttributes parameters are used to specify the key attributes data to be deleted on the KMS. Any number of attributes may be deleted in a single operation, regardless of whether the KMS supports multiple key attribute definitions in a single request or not. The KMS protocol implementation is responsible for generating the appropriate requests (single/multiple) to the KMS. In certain error situations, the status of each attribute is updated indicating if that attribute was successfully deleted or not.

The ClientDataSize and ClientData parameters allow the caller to pass an arbitrary block of data to/from the KMS for uses such as auditing or access control. The KMS protocol implementation does not alter this data block other than to package it for transmission to the KMS. The use of these parameters is optional unless the KMS requires it in order to perform the requested action.

Status Codes Returned

The DeleteKeyAttributes() function will return a status which indicates the overall status of the request. Note that this may be different from the status reported for individual key attribute requests. Status codes returned for the method are:

EFI_SUCCESS	Successfully deleted all requested key attributes.
EFI_OUT_OF_RESOURCES	Could not allocate required resources.
EFI_TIMEOUT	Timed out waiting for device or key server. Check individual key attribute request(s) to see which ones may have been processed.
EFI_ACCESS_DENIED	Access was denied by the device or the key server; OR a ClientId is required by the server and either none or an invalid id was provided
EFI_DEVICE_ERROR	Device or key server error. Check individual key attribute request(s) (i.e., key attribute status for each) to see which ones may have been processed.
EFI_INVALID_PARAMETER	This is NULL, ClientId is required but it is NULL , KeyAttributesCount is NULL, or KeyAttributes is NULL, or KeyIdentifierSize is NULL, or KeyIdentifer is NULL.
EFI_NOT_FOUND	The KeyIdentifier could not be found or the attribute could not be found. On return the KeyAttributesCount contains the number of attributes processed. Individual structures will reflect the status of the processing for that structure.
EFI_UNSUPPORTED	The implementation/KMS does not support this function

37.3.2.9. EFI_KMS_PROTOCOL.GetKeyByAttributes()

Summary

Retrieve one or more key that has matched all of the specified key attributes.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_KMS_GET_KEY_BY_ATTRIBUTES) (
  IN   EFI_KMS_PROTOCOL                  *This,
  IN   EFI_KMS_CLIENT_INFO               *Client,
  IN   UINTN                             *KeyAttributeCount,
  IN OUT EFI_KMS_KEY_ATTRIBUTE           *KeyAttributes,
  IN OUT UINTN                           *KeyDescriptorCount,
  IN OUT EFI_KMS_KEY_DESCRIPTOR          *KeyDescriptors,
  IN OUT UINTN                           *ClientDataSize OPTIONAL,
  IN OUT VOID                            **ClientData OPTIONAL
  );

Parameters

This: Pointer to this EFI_KMS_PROTOCOL instance.
Client: Pointer to a valid EFI_KMS_CLIENT_INFO structure.
KeyAttributeCount: Pointer to a count of the number of key attribute structures that must be matched for each returned key descriptor. On input the count value is one or more. On normal returns, this number will be updated with the number of key attributes successfully processed.
KeyAttributes: Pointer to an array of EFI_KMS_KEY_ATTRIBUTE structure to search for. On input, the values for the fields in the structure are completely filled in. On return the KeyAttributeStatus field will reflect the result of the operation for each key attribute request.
KeyDescriptorCount: Pointer to a count of the number of key descriptors matched by this operation. On entry, this number will be zero. On return, this number will be updated to the number of key descriptors successfully found.
KeyDescriptors: Pointer to an array of EFI_KMS_KEY_DESCRIPTOR structures which describe the keys from the KMS having the KeyAttribute(s) specified. On input, this pointer will be NULL. On output, the array will contain an EFI_KMS_KEY_DESCRIPTOR structure for each key meeting the search criteria. Memory for the array and all KeyValue fields will be allocated with the EfiBootServicesData type and must be freed by the caller when it is no longer needed. Also, the KeyStatus field of each descriptor will reflect the result of the request relative to that key descriptor.
ClientDataSize: Pointer to the size, in bytes, of an arbitrary block of data specified by the ClientData parameter. This parameter may be NULL, in which case the ClientData parameter will be ignored and no data will be transferred to or from the KMS. If the parameter is not NULL, then ClientData must be a valid pointer. If the value pointed to is 0, no data will be transferred to the KMS, but data may be returned by the KMS. For all non-zero values **ClientData* will be transferred to the KMS, which may also return data to the caller. In all cases, the value upon return to the caller will be the size of the data block returned to the caller, which will be zero if no data is returned from the KMS.
ClientData: Pointer to a pointer to an arbitrary block of data of **ClientDataSize* that is to be passed directly to the KMS if it supports the use of client data. This parameter may be NULL if and only if the ClientDataSize parameter is also NULL. Upon return to the caller, **ClientData* points to a block of data of **ClientDataSize* that was returned from the KMS. If the returned value for **ClientDataSize* is zero, then the returned value for **ClientData* must be NULL and should be ignored by the caller. The KMS protocol consumer is responsible for freeing all valid buffers used for client data regardless of whether they are allocated by the caller for input to the function or by the implementation for output back to the caller.

Description

The GetKeyByAttributes() function returns the keys found by searches for matching key attribute(s). This function must be supported by every KMS protocol instance that supports the use of key attributes as indicated in the protocol’s KeyAttributesSupported field.

The Client parameter identifies the caller to the key management service. It may be used for auditing or access control. The use of this parameter is optional unless the KMS requires it in order to perform the requested action.

The KeyAttributesCount and KeyAttributes parameters are used to specify the key attributes data to be searched for on the KMS. Any number of attributes may be searched for in a single operation, regardless of whether the KMS supports multiple key attribute definitions in a single request or not. The KMS protocol implementation is responsible for generating the appropriate requests (single/multiple) to the KMS. In certain error situations, the status of each attribute is updated indicating if that attribute was successfully found or not. If an attribute specifies a wildcard KeyAttributeInstance value, then the provider returns all instances of the attribute.

The KeyDescriptorCount and KeyDescriptors parameters are used to return the EFI_KMS_KEY_DESCRIPTOR structures for keys meeting the search criteria. Any number of keys may be returned in a single operation, regardless of whether the KMS supports multiple key definitions in a single request or not. The KMS protocol implementation is responsible for generating the appropriate requests (single/multiple) to the KMS.

The ClientDataSize and ClientData parameters allow the caller to pass an arbitrary block of data to/from the KMS for uses such as auditing or access control. The KMS protocol implementation does not alter this data block other than to package it for transmission to the KMS. The use of these parameters is optional unless the KMS requires it in order to perform the requested action.

Status Codes Returned

The GetKeyByAttributes() function will return a status which indicates the overall status of the request. Note that this may be different from the status reported for individual keys.

EFI_SUCCESS	Successfully retrieved all requested keys.
EFI_OUT_OF_RESOURCES	Could not allocate required resources.
EFI_TIMEOUT	Timed out waiting for device or key server. Check individual key attribute request(s) to see which ones may have been processed.
EFI_BUFFER_TOO_SMALL	If multiple keys are associated with the attribute(s), and the KeyValue buffer does not contain enough structures ( KeyDescriptorCount ) to contain all the key data, then the available structures will be filled and KeyDescriptorCount will be updated to indicate the number of keys which could not be processed.
EFI_ACCESS_DENIED	Access was denied by the device or the key server; OR a ClientId is required by the server and either none or an invalid id was provided
EFI_DEVICE_ERROR	Device or key server error. Check individual key attribute request(s) (i.e., key attribute status for each) to see which ones may have been processed.
EFI_INVALID_PARAMETER	This is NULL, ClientId is required but it is NULL , KeyDescriptorCount is NULL, or KeyDescriptors is NULL or KeyAttributes is NULL, or KeyAttributesCount is NULL .
EFI_NOT_FOUND	One or more EFI_KMS_KEY_ATTRIBUTE structures could not be processed properly. KeyAttributeCount contains the number of structures which were successfully processed. Individual structures will reflect the status of the processing for that structure.
EFI_UNSUPPORTED	The implementation/KMS does not support this function

37.4. PKCS7 Verify Protocol

37.4.1. EFI_PKCS7_VERIFY_PROTOCOL

Summary

EFI_PKCS7_VERIFY_PROTOCOL (See: http://tools.ietf.org/html/rfc2315 ) may be used to verify data signed with PKCS#7 formatted authentication. The PKCS#7 data to be verified must be binary DER encoded. Additional information on the supported ASN.1 formatting is provided below.

Drivers that supply PKCS7 verification function should publish the | EFI_PKCS7_VERIFY_PROTOCOL. Drivers wishing to use the | EFI_PKCS7_VERIFY_PROTOCOL may get a reference with LocateProtocol().

GUID

#define EFI_PKCS7_VERIFY_PROTOCOL_GUID \
  { 0x47889fb2, 0xd671, 0x4fab,\
    { 0xa0, 0xca, 0xdf, 0xe, 0x44,\ 0xdf, 0x70, 0xd6 }}

Protocol Interface Structure

typedef struct _EFI_PKCS7_VERIFY_PROTOCOL {
  EFI_PKCS7_VERIFY_BUFFER          *VerifyBuffer;
  EFI_PKCS7_VERIFY_SIGNATURE       *VerifySignature;
} EFI_PKCS7_VERIFY_PROTOCOL;

Parameters

VerifyBuffer: Examine a DER-encoded PKCS7-signed memory buffer with signature containing embedded data content, or buffer with detached signature and separate data content buffer, and verify using supplied signature lists.
VerifySignature: Examine a DER-encoded PKCS7-signed memory buffer with signature and, using caller-supplied hash value for signed data, verify using supplied signature lists.

Description

The EFI_PKCS7_VERIFY_PROTOCOL is used to verify data signed using PKCS7 structure. PKCS7 is a general-purpose cryptographic standard (see references). The PKCS7 data to be verified must be ASN.1 (DER) encoded. See the Table below.

Table 37.5 Details of Supported Signature Format
Signature Buffer Format Details
Encoding	Binary DER
ASN.1 root of Embedded Signed Data	ContentInfo with SignedData content type
ASN.1 root of Detached Signature	SignedData or ContentInfo with SignedData content type
Embedded Data Type	Typically ‘Data’ (1.2.840.113549.1.7.1) or other defined OID type (however caller should not depend upon specialized OID processing during PKCS validation.)
Digest (Hash) Algorithm ( VerifyBuffer function)	See [RFC2315] and OID definition by different standard bodies.
Digest Encryption	See [RFC2315] and OID definition by different standard bodies.
Certificate validity dates	See TimeStampDb description
Signature authenticatedAttributes	Ignored by function
Timestamping	See TimeStampDb description

References

PKCS7 is defined by RFC2315. For more information see “Links to UEFI-Related Documents” ( http://uefi.org/uefi ) under the heading “RFC2315 (defines PKCS7)”.

37.4.2. EFI_PKCS7_VERIFY_PROTOCOL.VerifyBuffer()

Summary

This function processes a buffer containing binary DER-encoded PKCS7 signature. The signed data content may be embedded within the buffer or separated. Function verifies the signature of the content is valid and signing certificate was not revoked and is contained within a list of trusted signers.

Prototype

typedef
EFI_STATUS
(EFIAPI *VerifyBuffer)(
  IN EFI_PKCS7_VERIFY_PROTOCOL         *This,
  IN VOID                              *SignedData,
  IN UINTN                             SignedDataSize,
  IN VOID                              *InData OPTIONAL,
  IN UINTN                             InDataSize
  IN EFI_SIGNATURE_LIST                **AllowedDb,
  IN EFI_SIGNATURE_LIST                **RevokedDb OPTIONAL,
  IN EFI_SIGNATURE_LIST                **TimeStampDb OPTIONAL,
  OUT VOID                             *Content OPTIONAL,
  IN OUT UINTN                         *ContentSize
  );

Parameters

This: Pointer to EFI_PKCS7_VERIFY_PROTOCOL instance.
SignedData: Points to buffer containing ASN.1 DER-encoded PKCS signature.
SignedDataSize: The size of SignedData buffer in bytes.
InData: In case of detached signature, Indata points to buffer containing the raw message data previously signed and to be verified by function. In case of SignedData containing embedded data, InData must be NULL.
InDataSize: When InData is used, the size of InData buffer in bytes.

When InData is NULL, this parameter must be 0.
AllowedDb: Pointer to a list of pointers to EFI_SIGNATURE_LIST structures. The list is terminated by a null pointer. The EFI_SIGNATURE_LIST structures contain lists of X.509 certificates of approved signers. See Chapter 27 for definition of EFI_SIGNATURE_LIST. Function recognizes signer certificates of type EFI_CERT_X509_GUID. Any hash certificate in AllowedDb list is ignored by this function. Function returns success if signer of the buffer is within this list (and not within RevokedDb ). This parameter is required.

RevokedDb: Optional pointer to a list of pointers to EFI_SIGNATURE_LIST structures. The list is terminated by a null pointer. List of X.509 certificates of revoked signers and revoked file hashes. Except as noted in description of TimeStampDb, signature verification will always fail if the signer of the file or the hash of the data component of the buffer is in RevokedDb list. This list is optional and caller may pass Null or pointer to NULL if not required.
TimeStampDb: Optional pointer to a list of pointers to EFI_SIGNATURE_LIST structures. The list is terminated by a null pointer. This parameter can be used to pass a list of X.509 certificates of trusted time stamp signers. This list is optional and caller may pass Null or pointer to NULL if not required.
Content: On input, points to an optional caller-allocated buffer into which the function will copy the content portion of the file after verification succeeds. This parameter is optional and if NULL, no copy of content from file is performed.
ContentSize: On input, points to the size in bytes of the optional buffer Content previously allocated by caller. On output, if the verification succeeds, the value referenced by ContentSize will contain the actual size of the content from signed file. If ContentSize indicates the caller-allocated buffer is too small to contain content, an error is returned, and ContentSize will be updated with the required size. This parameter must be 0 if Content is Null.

Description

This function processes the buffer SignedData for PCKS7 verification. The data that was signed using PKCS is referred to as the ‘Message’. In the process of creating a signature of the message, a SHA256 or other hash of the message bytes, called the ‘Message Digest’, is encrypted using a private key held in secret by the signer. The encrypted hash and the X.509 public key certificate of the signer are formatted according to the ASN.1 PKCS#7 Schema (See References). For the buffer type with the embedded data, the ASN.1 syntax is also used to wrap the data and combine the message data with the signature structure.

The SignedData buffer must be ASN.1 DER-encoded format with structure according to the subset defined in the introduction to this protocol. Both embedded content and detached signature formats are supported. In case of embedded content, SignedData contains both the PKCS7 signature structure and the message content that was signed. In the case of detached signature, SignedData contains only the signature data and InData is used to supply the data to be verified. To pass verification the X.509 public certificate of the signer of the file must be found in AllowedDb and not be present in RevokedDb. Additionally if RevokedDb contains a specific Hash signature that matches the hash calculated for the content, the file will also fail verification. The message content will be copied to the caller-supplied buffer Content (when present) with ContentSize updated to reflect the total size in bytes of the extracted content.

The VerifyBuffer() function performs several steps. First, the buffer containing the user-provided signature is parsed, the content is located and a hash calculated, and the PKCS7 signature of that hash is verified by decrypting the hash calculated at time of signing. Match of current hash with decrypted hash provides indication the structure contained in buffer has not been modified since signing. Next the protocol function attempts to match the signing certificate included within the signed data again the members of an (optional) list of caller-provided revoked certificates ( RevokedDb ). The hash of the data is also compared against any hash items contained in RevokedDb list. Next the signing certificate is matched against the caller-provided list of trusted signatures. If the signature is valid, the certificate or hash are not in the revoked list, and the certificate is in the trusted list, the file passes verification.

When TimeStampDb list is present this information modifies the processing of revoked certificates found in both AllowedDb and RevokedDb. When PCKS7 signings that are time-stamped by trusted signer in TimeStampDb list, and which time-stamping occurred prior to the time of certificate revocation noted in certificate in RevokedDb list, the signing will be allowed and return EFI_SUCCESS. TimeStampDb parameter is optional and may be NULL or a pointer to NULL when not used. Except in the processing of certificates found in both AllowedDb and RevokedDb, TimeStampDb is not used and time-stamping is not otherwise required for signings verified by certificate only in AllowedDb.

NOTE: This method is intended to be suitable to implement Secure Boot image validation, and as such the contents of AllowedDb, RevokedDb, and TimeStampDb must also conform with the requirements of Authorization Process , bullet item 3 (UEFI Image Validation Succeeded).

The verification function can handle both embedded data or detached signature formats. In case of embedded data, the function will optionally extract the original signed data and supply back to caller in caller-supplied buffer. For a detached signature the caller must provide the original message data in buffer pointed to by InData. For consistency, when both InData and Content are provided, the function will copy contents of InData to Content.

In case where the ContentSize indicated by caller is too small to contain the entire content extracted from the file, EFI_BUFFER_TOO_SMALL error is returned, and ContentSize is updated to reflect the required size.

NOTE: When signing certificate is matched to AllowedDb or RevokedDb lists, a match can occur against an entry in the list at any level of the chain of X.509 certificates present in the PCKS certificate list. This supports signing with a certificate that chains to one of the certificates in the AllowedDb or RevokedDb lists.

Related Definitions

None

Status Codes Returned

EFI_SUCCESS	Content signature was verified against hash of content, the signer’s certificate was not found in RevokedDb, and was found in AllowedDb or if in signer is found in both AllowedDb and RevokedDb, the signing was allowed by reference to TimeStampDb as described above, and no hash matching content hash was found in RevokedDb.
EFI_SECURITY_VIOLATION	The SignedData buffer was correctly formatted but signer was in RevokedDb or not in AllowedDb. Also returned if matching content hash found in RevokedDb.
EFI_COMPROMISED_DATA	Calculated hash differs from signed hash.
EFI_INVALID_PARAMETER	SIgnedData is NULL or SIgnedDataSize is zero. AllowedDb is NULL.
EFI_INVALID_PARAMETER	Content is not NULL and ContentSize is NULL.
EFI_ABORTED	Unsupported or invalid format in TImeStampDb, RevokedDb or AllowedDb list contents was detected.
EFI_NOT_FOUND	Content not found because InData is NULL and no content embedded in SIgnedData.
EFI_UNSUPPORTED	The SignedData buffer was not correctly formatted for processing by the function.
EFI_UNSUPPORTED	Signed data embedded in SIgnedData but InData is not NULL.
EFI_BUFFER_TOO_SMALL	The size of buffer indicated by ContentSize is too small to hold the content. ContentSize updated to required size.

37.4.2.1. EFI_PKCS7_VERIFY_PROTOCOL.VerifySignature()

Summary

This function processes a buffer containing binary DER-encoded detached PKCS7 signature. The hash of the signed data content is calculated and passed by the caller. Function verifies the signature of the content is valid and signing certificate was not revoked and is contained within a list of trusted signers.

Note

The current UEFI specification allows for a variety of hashes. In order to be secure, the users of this protocol should loop over each hash to see if the binary signature is authorized.

Prototype

typedef
EFI_STATUS
(EFIAPI *VerifySignature)(
  IN EFI_PKCS7_VERIFY_PROTOCOL      *This,
  IN VOID                           *Signature,
  IN UINTN                          SignatureSize,
  IN VOID                           *InHash,
  IN UINTN                          InHashSize
  IN EFI_SIGNATURE_LIST             **AllowedDb,
  IN EFI_SIGNATURE_LIST             **RevokedDb OPTIONAL,
  IN EFI_SIGNATURE_LIST             **TimeStampDb OPTIONAL,
  );

Parameters

This: Pointer to EFI_PKCS7_VERIFY_PROTOCOL instance.
Signature: Points to buffer containing ASN.1 DER-encoded PKCS detached signature.
SignatureSize: The size of Signature buffer in bytes.
InHash: InHash points to buffer containing the caller calculated hash of the data. This parameter may not be NULL.
InHashSize: The size in bytes of InHash buffer.
AllowedDb: Pointer to a list of pointers to EFI_SIGNATURE_LIST structures. The list is terminated by a null pointer. The EFI_SIGNATURE_LIST structures contain lists of X.509 certificates of approved signers. See Chapter 27 for definition of EFI_SIGNATURE_LIST. Function recognizes signer certificates of type EFI_CERT_X509_GUID. Any hash certificate in AllowedDb list is ignored by this function. Function returns success if signer of the buffer is within this list (and not within RevokedDb ). This parameter is required.

RevokedDb: Pointer to a list of pointers to EFI_SIGNATURE_LIST structures. The list is terminated by a null pointer. List of X.509 certificates of revoked signers and revoked file hashes. Signature verification will always fail if the signer of the file or the hash of the data component of the buffer is in RevokedDb list. This parameter is optional and caller may pass Null if not required.
TimeStampDb: Optional pointer to a list of pointers to EFI_SIGNATURE_LIST structures. The list is terminated by a null pointer. This parameter can be used to pass a list of X.509 certificates of trusted time stamp counter-signers.

Description

This function processes the buffer Signature for PCKS7 verification using hash of the data calculated and pass by caller in the InHash buffer. The data that was signed using PKCS is referred to as the ‘Message’. In the process of creating a signature of the message, a hash of the message bytes, called the ‘Message Digest’, is encrypted using a private key held in secret by the signer. The encrypted hash and the X.509 public key certificate of the signer are formatted according to the ASN.1 PKCS#7 Schema (See References). Any data embedded within the PKCS structure is ignored by the function. This function does not support extraction of signature from executable file formats. The address of the PKCS Signature block must be located and passed by the called.

The hash size passed in InHashSize must match the size of the signed hash embedded within the PKCS signature structure or an error is returned.

The SignedData buffer must be ASN.1 DER-encoded format with structure according to the subset defined in the introduction to this protocol. Both embedded content and detached signature formats are supported however embedded data is ignored. To pass verification the X.509 public certificate of the signer of the file must be found in AllowedDb and not be present in RevokedDb. Additionally, if RevokedDb contains a specific Hash signature that matches the hash calculated for the content, the file will also fail verification.

When TimeStampDb list is present this information modifies the processing of revoked certificates found in both AllowedDb and RevokedDb. When PCKS7 signings that are time-stanped by trusted signer in TimeStampDb list, and which time-stamping occurred prior to the time of certificate revocation noted in certificate in RevokedDb list, the signing will be allowed and return EFI_SUCCESS. TimeStampDb parameter is optional and may be NULL or a pointer to NULL when not used. Except in the processing of certificates found in both AllowedDb and RevokedDb, TimeStampDb is not used and time-stamping is not otherwise required for signings verified by certificate only in AllowedDb.

The VerifySignature() function performs several steps. First, the buffer containing the user-provided signature is parsed, (any embedded content is ignored), and the PKCS7 signature of hash data is verified by decrypting the hash calculated at time of signing. Match of caller provided hash with decrypted hash provides indication the signed data has not been modified since signing. Next the protocol function attempts to match the signing certificate included within the signed data again the members of an (optional) list of caller-provided revoked certificates ( RevokedDb ). The hash of the data is also compared against any hash items contained in RevokedDb list. Next the signing certificate is matched against the caller-provided list of trusted signatures. If the signature is valid, the certificate or hash are not in the revoked list, and the certificate is in the trusted list, the file passes verification.

Note

When a signing certificate is matched to AllowedDb or RevokedDb lists, a match can occur against an entry in the list at any level of the chain of X.509 certificates present in the PCKS certificate list. This supports signing with a certificate that chains to one of the certificates in the AllowedDb or RevokedDb lists.

Note

Because this function uses hashes and the specification contains a variety of hash choices, you should be aware that the check against the RevokedDb list will improperly succeed if the signature is revoked using a different hash algorithm. For this reason, you should either cycle through all UEFI supported hashes to see if one is forbidden, or rely on a single hash choice only if the UEFI signature authority only signs and revokes with a single hash.

Related Definitions

None

Status Codes Returned

EFI_SUCCESS	Signed hash was verified against caller-provided hash of content, the signer’s certificate was not found in RevokedDb, and was found in AllowedDb or if in signer is found in both AllowedDb and RevokedDb, the signing was allowed by reference to TimeStampDb as described above, and no hash matching content hash was found in RevokedDb.
EFI_SECURITY_VIOLATION	The SignedData buffer was correctly formatted but signer was in RevokedDb or not in AllowedDb. Also returned if matching content hash found in RevokedDb.
EFI_COMPROMISED_DATA	Caller provided hash differs from signed hash. Or, caller and encrypted hash are different sizes.
EFI_INVALID_PARAMETER	Signature is NULL or SignatureSize is zero. InHash is NULL or InhashSize is zero. AllowedDb is NULL.
EFI_ABORTED	Unsupported or invalid format in TimeStampDb, RevokedDb or AllowedDb list contents was detected.
EFI_UNSUPPORTED	The Signature buffer was not correctly formatted for processing by the function.

37.5. Random Number Generator Protocol

This section defines the Random Number Generator (RNG) protocol. This protocol is used to provide random numbers for use in applications, or entropy for seeding other random number generators. Consumers of the protocol can ensure that drivers implementing the protocol produce RNG values in a well-known manner.

When a Deterministic Random Bit Generator (DRBG) is used on the output of a (raw) entropy source, its security level must be at least 256 bits.

37.5.1. EFI_RNG_PROTOCOL

Summary

This protocol provides standard RNG functions. It can be used to provide random bits for use in applications, or entropy for seeding other random number generators.

GUID

#define EFI_RNG_PROTOCOL_GUID \
{ 0x3152bca5, 0xeade, 0x433d,\
  {0x86, 0x2e, 0xc0, 0x1c, 0xdc, 0x29, 0x1f, 0x44}}

Protocol Interface Structure

typedef struct _EFI_RNG_PROTOCOL {
  EFI_RNG_GET_INFO            GetInfo
  EFI_RNG_GET_RNG             GetRNG;
}  EFI_RNG_PROTOCOL;

Parameters

GetInfo: Returns information about the random number generation implementation.
GetRNG: Returns the next set of random numbers.

Description

This protocol allows retrieval of RNG values from an UEFI driver. The GetInfo service returns information about the RNG algorithms the driver supports. The GetRNG service creates a RNG value using an (optionally specified) RNG algorithm.

37.5.2. EFI_RNG_PROTOCOL.GetInfo

Summary

Returns information about the random number generation implementation.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_RNG_GET_INFO) (
  IN EFI_RNG_PROTOCOL            *This,
  IN OUT UINTN                   *RNGAlgorithmListSize,
  OUT EFI_RNG_ALGORITHM          *RNGAlgorithmList
  );

Parameters

This

A pointer to the EFI_RNG_PROTOCOL instance.

RNGAlgorithmListSize

On input, the size in bytes of RNGAlgorithmList. On output with a return code of EFI_SUCCESS, the size in bytes of the data returned in RNGAlgorithmList.

On output with a return code of EFI_BUFFER_TOO_SMALL, the size of RNGAlgorithmList required to obtain the list.

RNGAlgorithmList

A caller-allocated memory buffer filled by the driver with one EFI_RNG_ALGORITHM element for each supported RNG algorithm. The list must not change across multiple calls to the same driver. The first algorithm in the list is the default algorithm for the driver.

Description

This function returns information about supported RNG algorithms.

A driver implementing the RNG protocol need not support more than one RNG algorithm, but shall support a minimum of one RNG algorithm.

Related Definitions

typedef EFI_GUID EFI_RNG_ALGORITHM;

Status Codes Returned

EFI_SUCCESS	The RNG algorithm list was returned successfully.
EFI_UNSUPPORTED	The service is not supported by this driver.
EFI_DEVICE_ERROR	The list of algorithms could not be retrieved due to a hardware or firmware error.
EFI_BUFFER_TOO_SMALL	The buffer RNGAlgorithmList is too small to hold the result.

37.5.3. EFI_RNG_PROTOCOL.GetRNG

Summary

Produces and returns an RNG value using either the default or specified RNG algorithm.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_RNG_GET_RNG) (
  IN EFI_RNG_PROTOCOL            *This,
  IN EFI_RNG_ALGORITHM           *RNGAlgorithm, OPTIONAL
  IN UINTN                       RNGValueLength,
  OUT UINT8                      *RNGValue
  );

Parameters

This: A pointer to the EFI_RNG_PROTOCOL instance.
RNGAlgorithm: A pointer to the EFI_RNG_ALGORITHM that identifies the RNG algorithm to use. May be NULL in which case the function will use its default RNG algorithm.
RNGValueLength: The length in bytes of the memory buffer pointed to by RNGValue. The driver shall return exactly this number of bytes.
RNGValue: A caller-allocated memory buffer filled by the driver with the resulting RNG value.

Description

This function fills the RNGValue buffer with random bytes from the specified RNG algorithm. The driver must not reuse random bytes across calls to this function. It is the caller’s responsibility to allocate the RNGValue buffer.

Status Codes Returned

EFI_SUCCESS	The RNG value was returned successfully.
EFI_UNSUPPORTED	The algorithm specified by RNGAlgorithm is not supported by this driver.
EFI_DEVICE_ERROR	An RNG value could not be retrieved due to a hardware or firmware error.
EFI_NOT_READY	There is not enough random data available to satisfy the length requested by RNGValueLength.
EFI_INVALID_PARAMETER	RNGValue is null or RNGValueLength is zero.

37.5.4. EFI RNG Algorithm Definitions

Summary

This sub-section provides EFI_GUID values for a selection of EFI_RNG_PROTOCOL algorithms. The algorithms listed are optional, not meant to be exhaustive and may be augmented by vendors or other industry standards.

The “raw” algorithm, when supported, is intended to provide entropy directly from the source, without it going through some deterministic random bit generator.

Prototype

#define EFI_RNG_ALGORITHM_SP800_90_HASH_256_GUID \
 {0xa7af67cb, 0x603b, 0x4d42,\
 {0xba, 0x21, 0x70, 0xbf, 0xb6, 0x29, 0x3f, 0x96}}

#define EFI_RNG_ALGORITHM_SP800_90_HMAC_256_GUID \
 {0xc5149b43, 0xae85, 0x4f53,\
 {0x99, 0x82, 0xb9, 0x43, 0x35, 0xd3, 0xa9, 0xe7}}

#define EFI_RNG_ALGORITHM_SP800_90_CTR_256_GUID \
 {0x44f0de6e, 0x4d8c, 0x4045, \
 {0xa8, 0xc7, 0x4d, 0xd1, 0x68, 0x85, 0x6b, 0x9e}}

#define EFI_RNG_ALGORITHM_X9_31_3DES_GUID \
 {0x63c4785a, 0xca34, 0x4012,\
 {0xa3, 0xc8, 0x0b, 0x6a, 0x32, 0x4f, 0x55, 0x46}}

#define EFI_RNG_ALGORITHM_X9_31_AES_GUID \
 {0xacd03321, 0x777e, 0x4d3d,\
 {0xb1, 0xc8, 0x20, 0xcf, 0xd8, 0x88, 0x20, 0xc9}}

#define EFI_RNG_ALGORITHM_RAW \
 {0xe43176d7, 0xb6e8, 0x4827,\
   {0xb7, 0x84, 0x7f, 0xfd, 0xc4, 0xb6, 0x85, 0x61}}

37.5.5. RNG References

NIST SP 800-90, “Recommendation for Random Number Generation Using Deterministic Random Bit Generators,” March 2007. See “Links to UEFI-Related Documents” ( http://uefi.org/uefi ) under the heading “Recommendation for Random Number Generation Using Deterministic Random Bit Generators”.

NIST, “Recommended Random Number Generator Based on ANSI X9.31 Appendix A.2.4 Using the 3-Key Triple DES and AES Algorithms,” January 2005. See “Links to UEFI-Related Documents” ( http://uefi.org/uefi ) under the heading “Recommended Random Number Generator Based on ANSI X9.31”.

37.6. Smart Card Reader and Smart Card Edge Protocol

The UEFI Smart Card Reader Protocol provides an abstraction for device to provide smart card reader support. This protocol is very close to Part 5 of PC/SC workgroup specifications and provides an API to applications willing to communicate with a smart card or a smart card reader.

37.6.1. Smart Card Reader Protocol

37.6.1.1. EFI_SMART_CARD_READER_PROTOCOL Summary

Smart card aware application invokes this protocol to get access to an inserted smart card in the reader or to the reader itself.

GUID

#define EFI_SMART_CARD_READER_PROTOCOL_GUID \
  {0x2a4d1adf, 0x21dc, 0x4b81,\
  {0xa4, 0x2f, 0x8b, 0x8e, 0xe2, 0x38, 0x00, 0x60}}

Protocol Interface Structure

typedef struct _EFI_SMART_CARD_READER_PROTOCOL {
  EFI_SMART_CARD_READER_CONNECT           SCardConnect;
  EFI_SMART_CARD_READER_DISCONNECT        SCardDisconnect;
  EFI_SMART_CARD_READER_STATUS            SCardStatus;
  EFI_SMART_CARD_READER_TRANSMIT          SCardTransmit;
  EFI_SMART_CARD_READER_CONTROL           SCardControl;
  EFI_SMART_CARD_READER_GET_ATTRIB        SCardGetAttrib;
}   EFI_SMART_CARD_READER_PROTOCOL;

Members

SCardConnect: Requests a connection to the smart card or smart card reader.
SCardDisconnect: Closes the previously open connection.
SCardStatus: Provides informations on smart card status and reader name.
SCardTransmit: Exchanges data with smart card or smart card reader.
SCardControl: Gives direct control to the smart card reader.
SCardGetAttrib: Retrieves reader characteristics.

Description

This protocol allows UEFI applications to communicate and get/set all necessary information to the smart card reader.

Overview

This document aims at defining a standard way for UEFI applications to use a smart card. The key points are:

Provide an API as close as possible to Part 5 of the existing PC/SC interface. See “Links to UEFI-Related Documents” ( http://uefi.org/uefi ) under the heading “PC/SC Workgroup Specifications”.
Remove any unnecessary complexity of PC/SC implementation in a classic OS:

— Assume no connection sharing

— No resource manager

— Reduced set of APIs

Note that this document only focuses on PC/SC Part 5 (access to smart card/smart card reader from an application). Abstracting the smart card (Parts 6/9) is not the scope of this document.

Main differences with existing PC/SC implementation on Linux/MacOS/Windows:

There is no resource manager, driver exposes Part 5 instead of Part 3
It is not possible to share a smart card between UEFI applications/drivers
Reader enumeration is different:

— On classic PC/SC, SCardListReaders is used

— In UEFI, reader list is available via OpenProtocol/ScardStatus calls

37.6.2. EFI_SMART_CARD_READER_PROTOCOL.SCardConnect()

Summary

This function requests connection to the smart card or the reader, using the appropriate reset type and protocol.

Prototype

EFI_STATUS
  (EFIAPI *EFI_SMART_CARD_READER_PROTOCOL_CONNECT) (
  IN EFI_SMART_CARD_READER_PROTOCOL       *This,
  IN UINT32                               AccessMode,
  IN UINT32                               CardAction,
  IN UINT32                               PreferredProtocols,
  OUT UINT32                              *ActiveProtocol
  );

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_READER_PROTOCOL is defined in the EFI_SMART_CARD_READER_PROTOCOL description.
AccessMode: See “Related Definitions” below.
CardAction: SCARD_CA_NORESET,

SCARD_CA_COLDRESET or

SCARD_CA_WARMRESET.
PreferredProtocols: Bitmask of acceptable protocols. See “Related Definitions” below.
ActiveProtocol: A flag that indicates the active protocol. See “Related Definitions” below.

Related Definitions

//
// Codes for access mode
//
#define SCARD_AM_READER 0x0001 // Exclusive access to reader
#define SCARD_AM_CARD 0x0002 // Exclusive access to card
//
// Codes for card action
//
#define SCARD_CA_NORESET 0x0000 // Don’t reset card
#define SCARD_CA_COLDRESET 0x0001 // Perform a cold reset
#define SCARD_CA_WARMRESET 0x0002 // Perform a warm reset
#define SCARD_CA_UNPOWER 0x0003 // Power off the card
#define SCARD_CA_EJECT 0x0004 // Eject the card
//
// Protocol types
//
#define SCARD_PROTOCOL_UNDEFINED 0x0000
#define SCARD_PROTOCOL_T0 0x0001
#define SCARD_PROTOCOL_T1 0x0002
#define SCARD_PROTOCOL_RAW 0x0004

Description

The SCardConnect function requests access to the smart card or the reader. Upon success, it is then possible to call SCardTransmit.

If AccessMode is set to SCARD_AM_READER, PreferredProtocols must be set to SCARD_PROTOCOL_UNDEFINED and CardAction to SCARD_CA_NORESET else function fails with EFI_INVALID_PARAMETER.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL
EFI_INVALID_PARAMETER	AccessMode is not valid.
EFI_INVALID_PARAMETER	CardAction is not valid.
EFI_INVALID_PARAMETER	Invalid combination of AccessMode / CardAction / PreferredProtocols.
EFI_NOT_READY	A smart card is inserted but failed to return an ATR.
EFI_UNSUPPORTED	PreferredProtocols does not contain an available protocol to use.
EFI_NO_MEDIA	AccessMode is set to SCARD_AM_CARD but there is no smart card inserted.
EFI_ACCESS_DENIED	Access is already locked by a previous SCardConnect call.
EFI_DEVICE_ERROR	Any other error condition, typically a reader removal.

37.6.3. EFI_SMART_CARD_READER_PROTOCOL.SCardDisconnect()

Summary

This function releases a connection previously taken by SCardConnect.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_READER_PROTOCOL_DISCONNECT) (
IN EFI_SMART_CARD_READER_PROTOCOL         *This,
IN UINT32                                 CardAction
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_READER_PROTOCOL is defined in the EFI_SMART_CARD_READER_PROTOCOL description.
CardAction: See “Related Definitions” for CardAction in SCardConnect description.

Description

The SCardDisconnect function releases the lock previously taken by SCardConnect. In case the smart card has been removed before this call, this function returns EFI_SUCCESS. If there is no previous call to SCardConnect, this function returns EFI_SUCCESS.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL
EFI_INVALID_PARAMETER	CardAction value is unknown.
EFI_UNSUPPORTED	Reader does not support Eject card feature (disconnect was not performed).
EFI_DEVICE_ERROR	Any other error condition, typically a reader removal.

37.6.4. EFI_SMART_CARD_READER_PROTOCOL.SCardStatus()

Summary

This function retrieves some basic information about the smart card and reader.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_READER_PROTOCOL_STATUS) (
IN EFI_SMART_CARD_READER_PROTOCOL         *This,
OUT CHAR16                                *ReaderName OPTIONAL,
IN OUT UINTN                              *ReaderNameLength OPTIONAL,
OUT UINT32                                *State OPTIONAL,
OUT UINT32                                *CardProtocol OPTIONAL,
OUT UINT8                                 *Atr OPTIONAL,
IN OUT UINTN                              *AtrLength OPTIONAL
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_READER_PROTOCOL is defined in the EFI_SMART_CARD_READER_PROTOCOL description.
ReaderName: A pointer to a NULL terminated string that will contain the reader name.
ReaderNameLength: On input, a pointer to the variable that holds the maximal size, in bytes,of ReaderName.

On output, the required size, in bytes, for ReaderName.
State: Current state of the smart card reader. See “Related Definitions” below.
CardProtocol: Current protocol used to communicate with the smart card. See “Related Definitions” in SCardConnect.
Atr: A pointer to retrieve the ATR of the smart card.
AtrLength: On input, a pointer to hold the maximum size, in bytes, of Atr (usually 33).

On output, the required size, in bytes, for the smart card ATR.

Related Definitions

//
// Codes for state type
//
#define SCARD_UNKNOWN 0x0000 /* state is unknown */
#define SCARD_ABSENT 0x0001 /* Card is absent */
#define SCARD_INACTIVE 0x0002 /* Card is present and not powered*/
#define SCARD_ACTIVE 0x0003 /* Card is present and powered */

Description

The SCardStatus function retrieves basic reader and card information.

If ReaderName, State, CardProtocol or Atr is NULL, the function does not fail but does not fill in such variables.

If EFI_SUCCESS is not returned, ReaderName and Atr contents shall not be considered as valid.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL
EFI_INVALID_PARAMETER	ReaderName is not NULL but ReaderNameLength is NULL
EFI_INVALID_PARAMETER	Atr is not NULL but AtrLength is NULL
EFI_BUFFER_TOO_SMALL	ReaderNameLength is not big enough to hold the reader name. ReaderNameLength has been updated to the required value.
EFI_BUFFER_TOO_SMALL	AtrLength is not big enough to hold the ATR. AtrLength has been updated to the required value.
EFI_DEVICE_ERROR	Any other error condition, typically a reader removal.

37.6.5. EFI_SMART_CARD_READER_PROTOCOL.SCardTransmit()

Summary

This function sends a command to the card or reader and returns its response.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_READER_PROTOCOL_TRANSMIT) (
IN EFI_SMART_CARD_READER_PROTOCOL            *This,
IN UINT8                                     *CAPDU,
IN UINTN                                     CAPDULength,
OUT UINT8                                    *RAPDU,
IN OUT UINTN                                 *RAPDULength
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_READER_PROTOCOL is defined in the EFI_SMART_CARD_READER_PROTOCOL description.
CAPDU: A pointer to a byte array that contains the Command APDU to send to the smart card or reader.
CAPDULength: Command APDU size, in bytes.
RAPDU: A pointer to a byte array that will contain the Response APDU.
RAPDULength: On input, the maximum size, in bytes, of the Response APDU. On output, the size, in bytes, of the Response APDU.

Description

This function sends a command to the card or reader and returns its response. The protocol to use to communicate with the smart card has been selected through SCardConnect call.

In case RAPDULength indicates a buffer too small to hold the response APDU, the function fails with EFI_BUFFER_TOO_SMALL.

NOTE: the caller has to call previously SCardConnect to make sure the reader/card is not already accessed by another application or driver.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL
EFI_INVALID_PARAMETER	CAPDU is NULL or CAPDULength is 0.
EFI_BUFFER_TOO_SMALL	RAPDULength is not big enough to hold the response APDU. RAPDULength has been updated to the required value..
EFI_NO_MEDIA	There is no card in the reader.
EFI_NOT_READY	Card is not powered.
EFI_PROTOCOL_ERROR	A protocol error has occurred.
EFI_TIMEOUT	The reader did not respond.
EFI_ACCESS_DENIED	A communication with the reader/card is already pending.
EFI_DEVICE_ERROR	Any other error condition, typically a reader removal.

37.6.6. EFI_SMART_CARD_READER_PROTOCOL.SCardControl()

Summary

This function provides direct access to the reader.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_READER_PROTOCOL_CONTROL) (
IN EFI_SMART_CARD_READER_PROTOCOL         *This,
IN UINT32                                 ControlCode,
IN UINT8                                  *InBuffer OPTIONAL,
IN UINTN                                  InBufferLength OPTIONAL,
OUT UINT8                                 *OutBuffer OPTIONAL,
IN OUT UINTN                              *OutBufferLength OPTIONAL
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_READER_PROTOCOL is defined in the EFI_SMART_CARD_READER_PROTOCOL description.
ControlCode: The control code for the operation to perform. See “Related Definitions” below.
InBuffer: A pointer to the input parameters.
InBufferLength: Size, in bytes, of input parameters.
OutBuffer: A pointer to the output parameters.
OutBufferLength: On input, maximal size, in bytes, to store output parameters.

On output, the size, in bytes, of output parameters.

Description

This function gives direct control to send commands to the driver or the reader.

The ControlCode to use is vendor dependant; the only standard code defined is the one to get PC/SC part 10 features. See “Related Definitions” below.

InBuffer and Outbuffer may be NULL when ControlCode operation does not require them.

NOTE: the caller has to call previously SCardConnect to make sure the reader/card is not already accessed by another application or driver.

Related Definitions

//
// Macro to generate a ControlCode & PC/SC part 10 control code
//
#define SCARD_CTL_CODE(code) (0x42000000 + (code))
#define CM_IOCTL_GET_FEATURE_REQUEST SCARD_CTL_CODE(3400)

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL
EFI_INVALID_PARAMETER	ControlCode requires input parameters but: • InBuffer is NULL or InBufferLenth is NULL -or- • InBuffer is not NULL but InBufferLenth is less than
EFI_INVALID_PARAMETER	OutBuffer is not NULL but OutBufferLength is NULL
EFI_UNSUPPORTED	ControlCode is not supported.
EFI_BUFFER_TOO_SMALL	OutBufferLength is not big enough to hold the output parameters. OutBufferLength has been updated to the required value.
EFI_NO_MEDIA	There is no card in the reader and the control code specified requires one.
EFI_NOT_READY	ControlCode requires a powered card to operate.
EFI_PROTOCOL_ERROR	A protocol error has occurred.
EFI_TIMEOUT	The reader did not respond.
EFI_ACCESS_DENIED	A communication with the reader/card is already pending.
EFI_DEVICE_ERROR	Any other error condition, typically a reader removal.

37.6.7. EFI_SMART_CARD_READER_PROTOCOL.SCardGetAttrib()

Summary

This function retrieves a reader or smart card attribute.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_READER_PROTOCOL_GET_ATTRIB) (
IN EFI_SMART_CARD_READER_PROTOCOL         *This,
IN UINT32                                 Attrib,
OUT UINT8                                 *OutBuffer,
IN OUT UINTN                              *OutBufferLength
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_READER_PROTOCOL is defined in the EFI_SMART_CARD_READER_PROTOCOL description.
Attrib: Identifier for the attribute to retrieve. See “Related Definitions” below. Note that all attributes might not be implemented.
OutBuffer: A pointer to a buffer that will contain attribute data.
OutBufferLength: On input, maximal size, in bytes, to store attribute data.

On output, the size, in bytes, of attribute data.

Related Definitions

Possibly supported attrib values are listed in the PC/SC Specification, Part 3. See References for document link.

Description

The SCardGetAttrib function retrieves an attribute from the reader driver.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL
EFI_INVALID_PARAMETER	OutBuffer is NULL or OutBufferLength is 0.
EFI_BUFFER_TOO_SMALL	OutBufferLength is not big enough to hold the output parameters. OutBufferLength has been updated to the required value.
EFI_UNSUPPORTED	Attrib is not supported.
EFI_NO_MEDIA	There is no card in the reader and Attrib value requires one.
EFI_NOT_READY	Attrib requires a powered card to operate.
EFI_PROTOCOL_ERROR	A protocol error has occurred.
EFI_TIMEOUT	The reader did not respond.
EFI_DEVICE_ERROR	Any other error condition, typically a reader removal.

37.6.8. Smart Card Edge Protocol

The Smart Card Edge Protocol provides an abstraction for device to provide Smart Card support.

37.6.8.1. EFI_SMART_CARD_EDGE_PROTOCOL

Summary

Smart Card aware application invokes this protocol to get access to an inserted Smart Card in the reader.

GUID

#define EFI_SMART_CARD_EDGE_PROTOCOL_GUID \
{ 0xd317f29b, 0xa325, 0x4712,\
  { 0x9b, 0xf1, 0xc6, 0x19, 0x54, 0xdc, 0x19, 0x8c } }

Protocol Interface Structure

typedef struct _EFI_SMART_CARD_EDGE_PROTOCOL {
  EFI_SMART_CARD_EDGE_GET_CONTEXT         GetContext;
  EFI_SMART_CARD_EDGE_CONNECT             Connect;
  EFI_SMART_CARD_EDGE_DISCONNECT          Disconnect;
  EFI_SMART_CARD_EDGE_GET_CSN             GetCsn;
  EFI_SMART_CARD_EDGE_GET_READER_NAME     GetReaderName;
  EFI_SMART_CARD_EDGE_VERIFY_PIN          VerifyPin;
  EFI_SMART_CARD_EDGE_GET_PIN_REMAINING   GetPinRemaining;
  EFI_SMART_CARD_EDGE_GET_DATA            GetData;
  EFI_SMART_CARD_EDGE_GET_CREDENTIAL      GetCredential;
  EFI_SMART_CARD_EDGE_SIGN_DATA           SignData;
  EFI_SMART_CARD_EDGE_DECRYPT_DATA        DecryptData;
  EFI_SMART_CARD_EDGE_BUILD_DH_AGREEMENT  BuildDHAgreement;
}   EFI_SMART_CARD_EDGE_PROTOCOL;

Members

GetContext: Request the driver contex.
Connect: Request a connection to the Smart Card.
Disconnect: Close a previously open connection.
GetCSN: Get Card Serial Number.
GetReaderName: Get name of Smart Card reader used.
VerifyPin: Verify Smart Card PIN.
GetPinRemaining: Get number of remaining PIN tries.
GetData: Get specific data.
GetCredential: Get credentials the Smart Card holds.
SignData: Sign a data.
DecryptData: Decrypt a data.
BuildDHAgreement: Construct a DH (Diffie Hellman) agreement for key derivation.

Description

This protocol allows UEFI applications to interface with a Smart Card during boot process for authentication or data signing / decryption, especially if the application has to make use of PKI.

Overview

This document aims at defining a standard way for UEFI applications to use a Smart Card in PKI (Public Key Infrastructure) context. The key points are:

Each Smart Card or set of Smart Card have specific behavior.
Smart Card applications often interface with PKCS #11 API or other cryptographic interface like CNG.
During boot process not all the possibility of a cryptographic interface, like PKCS #11, are useful, for example it is neither the moment to perform Smart Card administration or Smart Card provisioning nor to process debit or credit operation with Smart Card.

Consequently this protocol focused on those points:

Offering standard access to Smart Card functionalities that:

— Authenticate User

— Sign data

— Decrypt data

— Get certificates
With an API that is enough close with PKCS#11 API that it could be considered as a brick to build a “tiny PKCS#11”.
An implementation of the protocol can be dedicated to a specific Smart Card or a specific set of Smart Card.
An implementation of the protocol shall poll for Smart Card reader attachment and removal.
An implementation of the protocol shall poll for Smart Card insertion and removal. On insertion the protocol shall check if it supports this Smart Card.

Typically an implementation of this protocol will lean on a Smart Card reader protocol ( EFI_SMART_CARD_READER_PROTOCOL ).

37.6.8.2. EFI_SMART_CARD_EDGE_PROTOCOL.GetContext()

Summary

This function retrieves the context driver.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_GET_CONTEXT) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL         *This,
  OUT UINTN                               *NumberAidSupported,
  IN OUT UINTN                            *AidTableSize OPTIONAL,
  OUT SMART_CARD_AID                      *AidTable OPTIONAL,
  OUT UINTN                               *NumberSCPresent,
  IN OUT UINTN                            *CsnTableSize OPTIONAL,
  OUT SMART_CARD_CSN                      *CsnTable OPTIONAL,
  OUT UINT32                              *VersionScEdgeProtocol OPTIONAL
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.
NumberAidSupported: Number of AIDs this protocol supports.
AidTableSize: On input, number of items allocated for the AID table.

On output, number of items returned by protocol.
AidTable: Table of the AIDs supported by the protocol.
NumberSCPresent: Number of currently present Smart Cards that are supported by protocol.
CsnTableSize: On input, the number of items the buffer CSN table can contain.

On output, the number of items returned by the protocol.
CsnTable: Table of the CSN of the Smart Card present and supported by protocol.
VersionScEdgeProtocol: EFI_SMART_CARD_EDGE_PROTOCOL version.

Related Definitions

//
// Maximum size for a Smart Card AID (Application IDentifier)
//
#define SCARD_AID_MAXSIZE 0x0010
//
// Size of CSN (Card Serial Number)
//
#define SCARD_CSN_SIZE 0x0010
//
//Current specification version 1.00
//
#define SMART_CARD_EDGE_PROTOCOL_VERSION_1 0x00000100

// Parameters type definition
//
typedef UINT8 SMART_CARD_AID[SCARD_AID_MAXSIZE];
typedef UINT8 SMART_CARD_CSN[SCARD_CSN_SIZE];

Description

The GetContext function returns the context of the protocol, the application identifiers supported by the protocol and the number and the CSN unique identifier of Smart Cards that are present and supported by protocol.

If AidTableSize, AidTable, CsnTableSize, CsnTable or VersionProtocol is NULL, the function does not fail but does not fill in such variables.

In case AidTableSize indicates a buffer too small to hold all the protocol AID table, only the first AidTableSize items of the table are returned in AidTable.

In case CsnTableSize indicates a buffer too small to hold the entire table of Smart Card CSN present, only the first CsnTableSize items of the table are returned in CsnTable.

VersionScEdgeProtocol returns the version of the EFI_SMART_CARD_EDGE_PROTOCOL this driver uses. For this protocol specification value is SMART_CARD_EDGE_PROTOCOL_VERSION_1.

In case of Smart Card removal the internal CSN list is immediately updated, even if a connection is opened with that Smart Card.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	NumberSCPresent Is NULL.

37.6.8.3. EFI_SMART_CARD_EDGE_PROTOCOL. Connect()

Summary

This function establish a connection with a Smart Card the protocol support.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_CONNECT) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL      *This,
  OUT EFI_HANDLE                       *SCardHandle,
  IN UINT8                             *ScardCsn OPTIONAL,
  OUT UINT8                            *ScardAid OPTIONAL
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.
SCardHandle: Handle on Smart Card connection.
ScardCsn: CSN of the Smart Card the connection has to be established.
ScardAid: AID of the Smart Card the connection has been established.

Description

The Connect function establishes a connection with a Smart Card.

In case of success the SCardHandle can be used.

If the ScardCsn is NULL the connection is established with the first Smart Card the protocol finds in its table of Smart Card present and supported. Else it establish context with the Smart Card whose CSN given by ScardCsn.

If ScardAid is not NULL the function returns the Smart Card AID the protocol supports.

After a successful connect the SCardHandle will remain existing even in case Smart Card removed from Smart Card reader, but all function invoking this SCardHandle will fail. SCardHandle is released only on Disconnect.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	SCardHandle is NULL.
EFI_NO_MEDIA	No Smart Card supported by protocol is present, Smart Card with CSN ScardCsn or Reader has been removed. A Disconnect should be performed.

37.6.8.4. EFI_SMART_CARD_EDGE_PROTOCOL.Disconnect()

Summary

This function releases a connection previously established by Connect.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_DISCONNECT) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL      *This,
  IN EFI_HANDLE                        SCardHandle
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.
SCardHandle: Handle on Smart Card connection to release.

Description

The Disconnect function releases the connection previously established by a Connect. In case the Smart Card or the Smart Card reader has been removed before this call, this function returns EFI_SUCCESS.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	No connection for SCardHandle value.

37.6.8.5. EFI_SMART_CARD_EDGE_PROTOCOL.GetCsn

Summary

This function returns the Smart Card serial number.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_GET_CSN) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL      *This,
  IN EFI_HANDLE                        SCardHandle,
  OUT UINT8                            Csn[SCARD_CSN_SIZE]
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.
SCardHandle: Handle on Smart Card connection.
Csn: The Card Serial number, 16 bytes array.

Description

The GetCsn function returns the 16 bytes Smart Card Serial number.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	No connection for SCardHandle value.
EFI_NO_MEDIA	Smart Card or Reader of SCardHandle connection has been removed. A Disconnect should be performed.

37.6.8.6. EFI_SMART_CARD_EDGE_PROTOCOL.GetReaderName

Summary

This function returns the name of the Smart Card reader used for this connection.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_GET_READER_NAME) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL                  *This,
  IN EFI_HANDLE                                    SCardHandle,
  IN OUT UINTN                                     *ReaderNameLength,
  OUT CHAR16                                       *ReaderName OPTIONAL
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.
SCardHandle: Handle on Smart Card connection.
ReaderNameLength: On input, a pointer to the variable that holds the maximal size, in bytes, of ReaderName.

On output, the required size, in bytes, for ReaderName.
ReaderName: A pointer to a NULL terminated string that will contain the reader name.

Description

The GetReaderName function returns the name of the Smart Card reader used for this connection.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	No connection for SCardHandle value.
EFI_INVALID_PARAMETER	ReaderNameLength is NULL.
EFI_NO_MEDIA	Smart Card or Reader of SCardHandle connection has been removed. A Disconnect should be performed.

37.6.8.7. EFI_SMART_CARD_EDGE_PROTOCOL.VerifyPin()

Summary

This function authenticates a Smart Card user by presenting a PIN code.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_VERIFY_PIN) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL         *This,
  IN EFI_HANDLE                           SCardHandle,
  IN INT32                                PinSize,
  IN UINT8                                *PinCode,
  OUT BOOLEAN                             *PinResult,
  OUT UINT32                              *RemainingAttempts OPTIONAL
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.
SCardHandle: Handle on Smart Card connection.
PinSize: PIN code buffer size.
PinCode: PIN code to present to the Smart Card.
PinResult: Result of PIN code presentation to the Smart Card.

TRUE when Smart Card founds the PIN code correct.
RemainingAttempts: Number of attempts still possible.

Description

The VerifyPin function presents a PIN code to the Smart Card.

If Smart Card found the PIN code correct the user is considered authenticated to current application, and the function returns TRUE.

Negative or null PinSize value rejected if PinCode is not NULL

A NULL PinCode buffer means the application didn’t know the PIN, in that case:

If PinSize value is negative the caller only wants to know if the current chain of the elements Smart Card Edge protocol, Smart Card Reader protocol and Smart Card Reader supports the Secure Pin Entry PCSC V2 functionality.
If PinSize value is positive or null the caller ask to perform the verify PIN using the Secure PIN Entry functionality.

In PinCode buffer, the PIN value is always given in plaintext, in case of secure messaging the SMART_CARD_EDGE_PROTOCOL will be in charge of all intermediate treatments to build the correct Smart Card APDU.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_UNSUPPORTED	Pinsize < 0 and Secure PIN Entry functionality not supported.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	No connection for SCardHandle value.
EFI_INVALID_PARAMETER	Bad value for PinSize : value not supported by Smart Card or, negative with PinCode not null.
EFI_INVALID_PARAMETER	PinResult is NULL.
EFI_NO_MEDIA	Smart Card or Reader of SCardHandle connection has been removed. A Disconnect should be performed.

37.6.8.8. EFI_SMART_CARD_EDGE_PROTOCOL.GetPinRemaining()

Summary

This function gives the remaining number of attempts for PIN code presentation.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_GET_PIN_REMAINING) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL      *This,
  IN EFI_HANDLE                        SCardHandle,
  OUT UINT32                           *RemainingAttempts
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.
SCardHandle: Handle on Smart Card connection.
RemainingAttempts: Number of attempts still possible.

Description

The number of attempts to present a correct PIN is limited and depends on Smart Card and on PIN.

This function will retrieve the number of remaining possible attempts.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	No connection for SCardHandle value.
EFI_INVALID_PARAMETER	RemainingAttempts is NULL.
EFI_NO_MEDIA	Smart Card or Reader of SCardHandle connection has been removed. A Disconnect should be performed.

37.6.8.9. EFI_SMART_CARD_EDGE_PROTOCOL.GetData()

Summary

This function returns a specific data from Smart Card.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_GET_DATA) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL      *This,
  IN EFI_HANDLE                        SCardHandle,
  IN EFI_GUID                          *DataId,
  IN OUT UINTN                         *DataSize,
  OUT VOID                             *Data OPTIONAL
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.
SCardHandle: Handle on Smart Card connection.
DataId: The type identifier of the data to get.
DataSize: On input, in bytes, the size of Data.

On output, in bytes, the size of buffer required to store the specified data.
Data: The data buffer in which the data is returned. The type of the data buffer is associated with the DataId. Ignored if DataSize is 0.

Description

This function returns a data from Smart Card. The function is generic for any kind of data, but driver and application must share an EFI_GUID that identify the data.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	No connection for SCardHandle value.
EFI_INVALID_PARAMETER	DataId is NULL.
EFI_INVALID_PARAMETER	DataSize is NULL.
EFI_INVALID_PARAMETER	Data is NULL, and DataSize is not zero.
EFI_NOT_FOUND	DataId unknown for this driver.
EFI_BUFFER_TOO_SMALL	The size of Data is too small for the specified data and the required size is returned in DataSize.
EFI_ACCESS_DENIED	Operation not performed, conditions not fulfilled. PIN not verified.
EFI_NO_MEDIA	Smart Card or Reader of SCardHandle connection has been removed. A Disconnect should be performed.

37.6.8.10. EFI_SMART_CARD_EDGE_PROTOCOL.GetCredentials()

Summary

This function retrieve credentials store into the Smart Card.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_GET_CREDENTIAL) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL         *This,
  IN EFI_HANDLE                           SCardHandle,
  IN OUT UINTN                            *CredentialSize,
  OUT UINT8                               *CredentialList OPTIONAL
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.
SCardHandle: Handle on Smart Card connection.
CredentialSize: On input, in bytes, the size of buffer to store the list of credential.

On output, in bytes, the size of buffer required to store the entire list of credentials.
CredentialList: List of credentials stored into the Smart Card. A list of TLV (Tag Length Value) elements organized in containers array.

Related Definitions

//Type of data elements in credentials list
#define SC_EDGE_TAG_HEADER 0x0000 \
        // value of tag field for header,
      // the number of containers
#define SC_EDGE_TAG_CERT 0x0001 // value of tag field for certificate
#define SC_EDGE_TAG_KEY_ID 0x0002 // value of tag field for key index
         // associated with certificate
#define SC_EDGE_TAG_KEY_TYPE 0x0003 // value of tag field for key type
#define SC_EDGE_TAG_KEY_SIZE 0x0004 // value of tag field for key size

//Length of L fields of TLV items
#define SC_EDGE_L_SIZE_HEADER 1 // size of L field for header
#define SC_EDGE_L_SIZE_CERT 2 // size of L field for certificate (big endian)
#define SC_EDGE_L_SIZE_KEY_ID 1 // size of L field for key index
#define SC_EDGE_L_SIZE_KEY_TYPE 1 // size of L field for key type
#define SC_EDGE_L_SIZE_KEY_SIZE 2 // size of L field for key size (big endian)

//Some TLV items have a fixed value for L field
#define SC_EDGE_L_VALUE_HEADER 1 // value of L field for header
#define SC_EDGE_L_VALUE_KEY_ID 1 // value of L field for key index
#define SC_EDGE_L_VALUE_KEY_TYPE 1 // value of L field for key type
#define SC_EDGE_L_VALUE_KEY_SIZE 2 // value of L field for key size

//Possible values for key type
#define SC_EDGE_RSA_EXCHANGE 0x01 //RSA decryption
#define SC_EDGE_RSA_SIGNATURE 0x02 //RSA signature
#define SC_EDGE_ECDSA_256 0x03 //ECDSA signature
#define SC_EDGE_ECDSA_384 0x04 //ECDSA signature
#define SC_EDGE_ECDSA_521 0x05 //ECDSA signature
#define SC_EDGE_ECDH_256 0x06 //ECDH agreement
#define SC_EDGE_ECDH_384 0x07 //ECDH agreement
#define SC_EDGE_ECDH_521 0x08 //ECDH agreement

Description

The function returns a series of items in TLV (Tag Length Value) format.

First TLV item is the header item that gives the number of following containers (0x00, 0x01, Nb containers).

All these containers are a series of 4 TLV items:

The certificate item (0x01, certificate size, certificate)
The Key identifier item (0x02, 0x01, key index)
The key type item (0x03, 0x01, key type)
The key size item (0x04, 0x02, key size), key size in number of bits.

Numeric multi-bytes values are on big endian format, most significant byte first:

The L field value for certificate (2 bytes)
The L field value for key size (2 bytes)
The value field for key size (2 bytes)

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	No connection for SCardHandle value.
EFI_INVALID_PARAMETER	CredentialSize is NULL.
EFI_INVALID_PARAMETER	CredentialList is NULL, if CredentialSize is not zero.
EFI_BUFFER_TOO_SMALL	The size of CredentialList is too small for the specified data and the required size is returned in CredentialSize.
EFI_NO_MEDIA	Smart Card or Reader of SCardHandle connection has been removed. A Disconnect should be performed.

37.6.8.11. EFI_SMART_CARD_EDGE_PROTOCOL.SignData()

Summary

This function signs an already hashed data with a Smart Card private key.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_SIGN_DATA) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL   *This,
  IN EFI_HANDLE                     SCardHandle,
  IN UINTN                          KeyId,
  IN UINTN                          KeyType,
  IN EFI_GUID                       *HashAlgorithm,
  IN EFI_GUID                       *PaddingMethod,
  IN UINT8                          *HashedData,
  OUT UINT8                         *SignatureData
);

Parameters

This

Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.

SCardHandle

Handle on Smart Card connection.

KeyId

Identifier of the key container, retrieved in a key index item of credentials.

KeyType

The key type, retrieved in a key type item of credentials.

HashAlgorithm

Hash algorithm used to hash the, one of:

EFI_HASH_ALGORITHM_SHA1_GUID
EFI_HASH_ALGORITHM_SHA256_GUID
EFI_HASH_ALGORITHM_SHA384_GUID
EFI_HASH_ALGORITHM_SHA512_GUID

PaddingMethod

Padding method used jointly with hash algorithm, one of:

EFI_PADDING_RSASSA_PKCS1V1P5_GUID
EFI_PADDING_RSASSA_PSS_GUID

HashedData

Hash of the data to sign. Size is function of the HashAlgorithm.

SignatureData

Resulting signature with private key KeyId. Size is function of the KeyType and key size retrieved in the associated key size item of credentials.

Related Definitions

//
// Padding methods GUIDs for signature
//

//
// RSASSA- PKCS#1-V1.5 padding method, for signature
//
#define EFI_PADDING_RSASSA_PKCS1V1P5_GUID \
{0x9317ec24,0x7cb0,0x4d0e,\
{0x8b,0x32,0x2e,0xd9,0x20,0x9c,0xd8,0xaf}}

//
// RSASSA-PSS padding method, for signature
//
#define EFI_PADDING_RSASSA_PSS_GUID \
{0x7b2349e0,0x522d,0x4f8e,\
{0xb9,0x27,0x69,0xd9,0x7c,0x9e,0x79,0x5f}}

Description

This function signs data, actually it is the hash of these data that is given to the function.

SignatureData buffer shall be big enough for signature. Signature size is function key size and key type.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	No connection for SCardHandle value.
EFI_INVALID_PARAMETER	KeyId is not valid.
EFI_INVALID_PARAMETER	KeyType is not valid or not corresponding to KeyId.
EFI_INVALID_PARAMETER	HashAlgorithm is NULL.
EFI_INVALID_PARAMETER	HashAlgorithm is not valid.
EFI_INVALID_PARAMETER	PaddingMethod is NULL.
EFI_INVALID_PARAMETER	PaddingMethod is not valid.
EFI_INVALID_PARAMETER	HashedData is NULL.
EFI_INVALID_PARAMETER	SignatureData is NULL.
EFI_ACCESS_DENIED	Operation not performed, conditions not fulfilled. PIN not verified.
EFI_NO_MEDIA	Smart Card or Reader of SCardHandle connection has been removed. A Disconnect should be performed.

37.6.8.12. EFI_SMART_CARD_EDGE_PROTOCOL.DecryptData()

Summary

This function decrypts data with a PKI/RSA Smart Card private key.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_DECRYPT_DATA) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL      *This,
  IN EFI_HANDLE                        SCardHandle,
  IN UINTN                             KeyId,
  IN EFI_GUID                          *HashAlgorithm,
  IN EFI_GUID                          *PaddingMethod,
  IN UINTN                             EncryptedSize,
  IN UINT8                             *EncryptedData,
  IN OUT UINTN                         *PlaintextSize,
  OUT UINT8                            *PlaintextData
);

Parameters

This

Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.

SCardHandle

Handle on Smart Card connection.

KeyId

Identifier of the key container, retrieved in a key index item of credentials.

HashAlgorithm

Hash algorithm used to hash the, one of:

EFI_HASH_ALGORITHM_SHA1_GUID
EFI_HASH_ALGORITHM_SHA256_GUID
EFI_HASH_ALGORITHM_SHA384_GUID
EFI_HASH_ALGORITHM_SHA512_GUID

PaddingMethod

Padding method used jointly with hash algorithm, one of:

EFI_PADDING_NONE_GUID
EFI_PADDING_RSAES_PKCS1V1P5_GUID
EFI_PADDING_RSAES_OAEP_GUID

EncryptedSize

Size of data to decrypt

EncryptedData

Data to decrypt

PlaintextSize

On input, in bytes, the size of buffer to store the decrypted data.

On output, in bytes, the size of buffer required to store the decrypted data.

PlaintextData

Buffer for decrypted data, padding removed.

Related Definitions

//
// Padding methods GUIDs for decryption
//

//
// No padding, for decryption
//
#define EFI_PADDING_NONE_GUID \
{0x3629ddb1,0x228c,0x452e,\
{0xb6,0x16,0x09,0xed,0x31,0x6a,0x97,0x00}}

//
// RSAES-PKCS#1-V1.5 padding, for decryption
//
#define EFI_PADDING_RSAES_PKCS1V1P5_GUID \
{0xe1c1d0a9,0x40b1,0x4632,\
{0xbd,0xcc,0xd9,0xd6,0xe5,0x29,0x56,0x31}}

//
// RSAES-OAEP padding, for decryption
//
#define EFI_PADDING_RSAES_OAEP_GUID \
{0xc1e63ac4,0xd0cf,0x4ce6,\
{0x83,0x5b,0xee,0xd0,0xe6,0xa8,0xa4,0x5b}}

Description

The function decrypts some PKI / RSA encrypted data with private key securely stored into the Smart Card.

The KeyId must reference a key of type SC_EDGE_RSA_EXCHANGE.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	No connection for SCardHandle value.
EFI_INVALID_PARAMETER	KeyId is not valid or associated key not of type SC_EDGE_RSA_EXCHANGE.
EFI_INVALID_PARAMETER	HashAlgorithm is NULL.
EFI_INVALID_PARAMETER	HashAlgorithm is not valid.
EFI_INVALID_PARAMETER	PaddingMethod is NULL.
EFI_INVALID_PARAMETER	PaddingMethod is not valid.
EFI_INVALID_PARAMETER	EncryptedSize is 0.
EFI_INVALID_PARAMETER	EncryptedData is NULL.
EFI_INVALID_PARAMETER	PlaintextSize is NULL.
EFI_INVALID_PARAMETER	PlaintextData is NULL.
EFI_ACCESS_DENIED	Operation not performed, conditions not fulfilled. PIN not verified.
EFI_BUFFER_TOO_SMALL	PlaintextSize is too small for the plaintext data and the required size is returned in PlaintextSize.
EFI_NO_MEDIA	Smart Card or Reader of SCardHandle connection has been removed. A Disconnect should be performed.

37.6.8.13. EFI_SMART_CARD_EDGE_PROTOCOL.BuildDHAgreement()

Summary

This function performs a secret Diffie Hellman agreement calculation that would be used to derive a symmetric encryption / decryption key.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SMART_CARD_EDGE_BUILD_DH_AGREEMENT) (
  IN EFI_SMART_CARD_EDGE_PROTOCOL      *This,
  IN EFI_HANDLE                        SCardHandle,
  IN UINTN                             KeyId,
  IN UINT8                             *dataQx,
  IN UINT8                             *dataQy,
  OUT UINT8                            *DHAgreement
);

Parameters

This: Indicates a pointer to the calling context. Type EFI_SMART_CARD_EDGE_PROTOCOL is defined in the EFI_SMART_CARD_EDGE_PROTOCOL description.
SCardHandle: Handle on Smart Card connection.
KeyId: Identifier of the key container, retrieved in a key index item of credentials.
dataQx: Public key x coordinate. Size is the same as key size for KeyId. Stored in big endian format.
dataQy: Public key y coordinate. Size is the same as key size for KeyId. Stored in big endian format.
DHAgreement: Buffer for DH agreement computed. Size must be bigger or equal to key size for KeyId.

Description

The function compute a DH agreement that should be diversified to generate a symmetric key to proceed encryption or decryption.

The application and the Smart Card shall agree on the diversification process.

The KeyId must reference a key of one of the types: SC_EDGE_ECDH_256, SC_EDGE_ECDH_384 or SC_EDGE_ECDH_521.

Status Codes Returned

EFI_SUCCESS	The requested command completed successfully.
EFI_INVALID_PARAMETER	This is NULL.
EFI_INVALID_PARAMETER	No connection for SCardHandle value.
EFI_INVALID_PARAMETER	KeyId is not valid.
EFI_INVALID_PARAMETER	dataQx is NULL.
EFI_INVALID_PARAMETER	dataQy is NULL.
EFI_INVALID_PARAMETER	DHAgreement is NULL.
EFI_ACCESS_DENIED	Operation not performed, conditions not fulfilled. PIN not verified.
EFI_NO_MEDIA	Smart Card or Reader of SCardHandle connection has been removed. A Disconnect should be performed.

37.7. Memory Protection

37.7.1. EFI_MEMORY_ATTRIBUTE PROTOCOL

Summary

This protocol abstracts the memory attributes setting or getting in UEFI environment.

GUID

#define EFI_MEMORY_ATTRIBUTE_PROTOCOL_GUID \
  {0xf4560cf6, 0x40ec, 0x4b4a, 0xa1, 0x92, 0xbf, 0x1d, 0x57, 0xd0,
0xb1, 0x89}

Protocol Interface Structure

typedef struct _EFI_MEMORY_ATTRIBUTE_PROTOCOL {
  EFI_GET_MEMORY_ATTRIBUTES          GetMemoryAttributes;
  EFI_SET_MEMORY_ATTRIBUTES          SetMemoryAttributes;
  EFI_CLEAR_MEMORY_ATTRIBUTES        ClearMemoryAttributes;
} EFI_MEMORY_ATTRIBUTE_PROTOCOL;

Parameters

GetMemoryAttributes: Get the memory attributes for a memory region. See the GetMemoryAttrbutes() function description.
SetMemoryAttributes: Set the memory attributes for a memory region. See the SetMemoryAttrbutes() function description.
ClearMemoryAttributes: Clear the memory attributes for a memory region. See the ClearMemoryAttrbutes() function description.

Description

The EFI_MEMORY_ATTRIBUTE_PROTOCOL is used to abstract memory attribute access for a memory region.

37.7.1.1. EFI_MEMORY_ATTRIBUTE_PROTOCOL.GetMemoryAttributes

Summary

This service retrieves the memory attributes of a memory region.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_GET_MEMORY_ATTRIBUTES)(
  IN EFI_MEMORY_ATTRIBUTE_PROTOCOL  *This,
  IN EFI_PHYSICAL_ADDRESS           BaseAddress,
  IN UINT64                         Length,
  OUT UINT64                        *Attributes
  );

Parameters

This: The protocol interface pointer.
BaseAddress: The physical address that is the start address of a memory region.
Length: The size in bytes of the memory region.
Attributes: Pointer to the bit mask of memory attributes returned. The bit mask of attributes is defined in the GetMemoryMap() function description in the UEFI 2.0 specification. The valid Attributes is EFI_MEMORY_R, EFI_MEMORY_XP, and EFI_MEMORY_RO.

Description

This function retrieves the attributes of the memory region specified by BaseAddress and Length. If different attributes are got from different part of the memory region, EFI_NO_MAPPING will be returned.

Status Code Returned

EFI_SUCCESS	The attributes are got for the memory region.
EFI_INVALID_PARAMETER	`Length` is zero. `Attributes` is NULL.
EFI_NO_MAPPING	Attributes are not consistent across the memory region.
EFI_UNSUPPORTED	The processor does not support one or more bytes of the memory resource range specified by `BaseAddress` and `Length`.

37.7.1.2. EFI_MEMORY_ATTRIBUTE_PROTOCOL.SetMemoryAttributes

Summary

This service sets the memory attributes of a memory region.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_SET_MEMORY_ATTRIBUTES)(
  IN EFI_MEMORY_ATTRIBUTE_PROTOCOL  *This,
  IN EFI_PHYSICAL_ADDRESS           BaseAddress,
  IN UINT64                         Length,
  IN UINT64                         Attributes
  );

Parameters

This: The protocol interface pointer.
BaseAddress: The physical address that is the start address of a memory region.
Length: The size in bytes of the memory region.
Attributes: The bit mask of memory attributes. The bit mask of attributes is defined in the GetMemoryMap() function description in the UEFI 2.0 specification. The valid Attributes is EFI_MEMORY_RP, EFI_MEMORY_XP, and EFI_MEMORY_RO.

Description

This function sets the given attributes of the memory region specified by BaseAddress and Length. This function only adds new attributes with the bit mask 1 and ignores the attributes with the bit mask 0.

Status Codes Returned

EFI_SUCCESS	The attributes are set for the memory region.
EFI_INVALID_PARAMETER	`Length` is zero. `Attributes` specified an illegal combination of attributes that cannot be set together..
EFI_UNSUPPORTED	The processor does not support one or more bytes of the memory resource range specified by `BaseAddress` and `Length`. The bit mask of attributes is not supported for the memory resource range specified by `BaseAddress` and `Length`.
EFI_OUT_OF_RESOURCES	Requested attributes cannot be applied due to luck of system resources.
EFI_ACCESS_DENIED	Attributes for the requested memory region are controlled by system firmware and cannot be updated via the protocol.

37.7.1.3. EFI_MEMORY_ATTRIBUTE_PROTOCOL.ClearMemoryAttributes

Summary

This service clears the memory attributes of a memory region.

Prototype

typedef
EFI_STATUS
(EFIAPI *EFI_CLEAR_MEMORY_ATTRIBUTES)(
  IN EFI_MEMORY_ATTRIBUTE_PROTOCOL  *This,
  IN EFI_PHYSICAL_ADDRESS           BaseAddress,
  IN UINT64                         Length,
  IN UINT64                         Attributes
  );

Parameters

This: The protocol interface pointer.
BaseAddress: The physical address that is the start address of a memory region.
Length: The size in bytes of the memory region.
Attributes: The bit mask of memory attributes. The bit mask of attributes is defined in the GetMemoryMap() function description in the UEFI 2.0 specification. The valid Attributes is EFI_MEMORY_RP, EFI_MEMORY_XP, and EFI_MEMORY_RO.

Description

This function clears the given attributes of the memory region specified by BaseAddress and Length. This function only removes new attributes with the bit mask 1 and ignore the attributes with the bit mask 0.

Status Codes Returned

EFI_SUCCESS	The attributes are cleared for the memory region.
EFI_INVALID_PARAMETER	`Length` is zero. `Attributes` specified an illegal combination of attributes that cannot be cleared together..
EFI_UNSUPPORTED	The processor does not support one or more bytes of the memory resource range specified by `BaseAddress` and `Length`. The bit mask of attributes is not supported for the memory resource range specified by `BaseAddress` and `Length`.
EFI_OUT_OF_RESOURCES	Requested attributes cannot be applied due to luck of system resources.
EFI_ACCESS_DENIED	Attributes for the requested memory region are controlled by system firmware and cannot be updated via the protocol.